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• Silverlight Reporting Application Part 3.5 - Prism Background and WCF RIA [Series Intermission]

  Taking a step back before I dive into the details and full-on coding fun, I wanted to once again respond to a comment on my last post to clear up some things in regards to how I'm setting up my project and some of the choices I've made. Aka, thanks Ben. :) Prism Project Setup For starters, I'm not the ideal use case for a Prism application. In most cases where you've got a one-man team, Prism can be overkill as it is more intended for large teams who are geographically dispersed or in applications that have a larger scale than my Recruiting application in which you'll greatly benefit from modularity, delayed loading of xaps, etc. What Prism offers, though, is a manner for handling UI, commands, and events with the idea that, through a modular approach in which no parts really need to know about one another, I can update this application bit by bit as hiring needs change or requirements differ between offices without having to worry that changing something in the Jobs module will break something in, say, the Scheduling module. All that being said, here's a look at how our project breakdown for Recruit (MVVM/Prism implementation) looks: This could be a little misleading though, as each of those modules is actually another project in the overall Recruit solution. As far as what the projects actually are, that looks a bit like this: Recruiting Solution Recruit (Shell up there) - Main Silverlight Application .Web - Default .Web application to host the Silverlight app Infrastructure - Silverlight Class Library Project Modules - Silverlight Class Library Projects Infrastructure &Modules The Infrastructure project is probably something you'll see to some degree in any composite application. In this application, it is going to contain custom commands (you'll see the joy of these in a post or two down the road), events, helper classes, and any custom classes I need to share between different modules. Think of this as a handy little crossroad between any parts of your application. Modules on the other hand are the bread and butter of this application. Besides the shell, which holds the UI skeleton, and the infrastructure, which holds all those shared goodies, the modules are self-contained bundles of functionality to handle different concerns. In my scenario, I need a way to look up and edit Jobs, Applicants, and Schedule interviews, a Notification module to handle telling the user when different things are happening (i.e., loading from database), and a Menu to control interaction and moving between different views. All modules are going to follow the following pattern: The module class will inherit from IModule and handle initialization and loading the correct view into the correct region, whereas the Views and ViewModels folders will contain paired Silverlight user controls and ViewModel class backings. WCF RIA Services Since we've got all the projects in a single solution, we did not have to go the route of creating a WCR RIA Services Class Library. Every module has it's WCF RIA link back to the main .Web project, so the single Linq-2-SQL (yes, I said Linq-2-SQL, but I'll soon be switching to OpenAccess due to the new visual designer) context I'm using there works nicely with the scope of my project. If I were going for completely separating this project out and doing different, dynamically loaded elements, I'd probably go for the separate class library. Hope that clears that up. In the future though, I will be using that in a project that I've got in the "when I've got enough time to work on this" pipeline, so we'll get into that eventually- and hopefully when WCF RIA is in full release! Why Not use Silverlight Navigation/Business Template? The short answer- I'm a creature of habit, and having used Silverlight for a few years now, I'm used to doing lots of things manually. :) Plus, starting with a blank slate of a project I'm able to set up things exactly as I want them to be. In this case, rather than the navigation frame we would see in one of the templates, the MainRegion/ContentControl is working as our main navigation window. In many cases I will use theSilverlight navigation template to start things off, however in this case I did not need those features so I opted out of using that. Next time when I actually hit post #4, we're going to get into the modules and starting to get functionality into this application. Next week is also release week for the Q1 2010 release, so be sure to check out our annualWebinar Week (I might be biased, but Wednesday is my favorite out of the group). Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Loading XML file containing leading zeros with SSIS preserving the zeros

  - by Compudicted

  Visiting the MSDN SQL Server Integration Services Forum oftentimes I could see that people would pop up asking this question: “why I am not able to load an element from an XML file that contains zeros so the leading/trailing zeros would remain intact?”. I started to suspect that such a trivial and often-required operation perhaps is being misunderstood by the developer community. I would also like to add that the whole state of affairs surrounding the XML today is probably also going to be increasingly affected by a motion of people who dislike XML in general and many aspects of it as XSD and XSLT invoke a negative reaction at best. Nevertheless, XML is in wide use today and its importance as a bridge between diverse systems is ever increasing. Therefore, I deiced to write up an example of loading an arbitrary XML file that contains leading zeros in one of its elements using SSIS so the leading zeros would be preserved keeping in mind the goal on simplicity into a table in SQL Server database. To start off bring up your BIDS (running as admin) and add a new Data Flow Task (DFT). This DFT will serve as container to adding our XML processing elements (besides, the XML Source is not available anywhere else other than from within the DFT). Double-click your DFT and drag and drop the XMS Source component from the Tool Box’s Data Flow Sources. Now, let the fun begin! Being inspired by the upcoming Christmas I created a simple XML file with one set of data that contains an imaginary SSN number of Rudolph containing several leading zeros like 0000003. This file can be viewed here. To configure the XML Source of course it is quite intuitive to point it to our XML file, next what the XML source needs is either an embedded schema (XSD) or it can generate one for us. In lack of the one I opted to auto-generate it for me and I ended up with an XSD that looked like: <?xml version="1.0"?> <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="XMasEvent"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="CaseInfo"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="ID" type="xs:unsignedByte" /> <xs:element minOccurs="0" name="CreatedDate" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="LastName" type="xs:string" /> <xs:element minOccurs="0" name="FirstName" type="xs:string" /> <xs:element minOccurs="0" name="SSN" type="xs:unsignedByte" /> <!-- Becomes string -- > <xs:element minOccurs="0" name="DOB" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="Event" type="xs:string" /> <xs:element minOccurs="0" name="ClosedDate" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> As an aside on the XML file: if your XML file does not contain the outer node (<XMasEvent>) then you may end up in a situation where you see just one field in the output. Now please note that the SSN element’s data type was chosen to be of unsignedByte (and this is for a reason). The reason is stemming from the fact all our figures in the element are digits, this is good, but this is not exactly what we need, because if we will attempt to load the data with this XSD then we are going to either get errors on the destination or most typically lose the leading zeros. So the next intuitive choice is to change the data type to string. Besides, if a SSIS package was already created based on this XSD and the data type change was done thereafter, one should re-set the metadata by right-clicking the XML Source and choosing “Advanced Editor” in which there is a refresh button at the bottom left which will do the trick. So far so good, we are ready to load our XML file, well actually yes, and no, in my experience typically some data conversion may be required. So depending on your data destination you may need to tweak the data types targeted. Let’s add a Data Conversion Task to our DFT. Your package should look like: To make the story short I only will cover the SSN field, so in my data source the target SQL Table has it as nchar(10) and we chose string in our XSD (yes, this is a big difference), under such circumstances the SSIS will complain. So will go and manipulate on the data type of SSN by making it Unicode String (DT_WSTR), World String per se. The conversion should look like: The peek at the Metadata: We are almost there, now all we need is to configure the destination. For simplicity I chose SQL Server Destination. The mapping is a breeze, F5 and I am able to insert my data into SQL Server now! Checking the zeros – they are all intact!

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• NetBeans, JSF, and MySQL Primary Keys using AUTO_INCREMENT

  - by MarkH

  I recently had the opportunity to spin up a small web application using JSF and MySQL. Having developed JSF apps with Oracle Database back-ends before and possessing some small familiarity with MySQL (sans JSF), I thought this would be a cakewalk. Things did go pretty smoothly...but there was one little "gotcha" that took more time than the few seconds it really warranted. The Problem Every DBMS has its own way of automatically generating primary keys, and each has its pros and cons. For the Oracle Database, you use a sequence and point your Java classes to it using annotations that look something like this: @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="POC_ID_SEQ") @SequenceGenerator(name="POC_ID_SEQ", sequenceName="POC_ID_SEQ", allocationSize=1) Between creating the actual sequence in the database and making sure you have your annotations right (watch those typos!), it seems a bit cumbersome. But it typically "just works", without fuss. Enter MySQL. Designating an integer-based field as PRIMARY KEY and using the keyword AUTO_INCREMENT makes the same task seem much simpler. And it is, mostly. But while NetBeans cranks out a superb "first cut" for a basic JSF CRUD app, there are a couple of small things you'll need to bring to the mix in order to be able to actually (C)reate records. The (RUD) performs fine out of the gate. The Solution Omitting all design considerations and activity (!), here is the basic sequence of events I followed to create, then resolve, the JSF/MySQL "Primary Key Perfect Storm": Fire up NetBeans. Create JSF project. Create Entity Classes from Database. Create JSF Pages from Entity Classes. Test run. Try to create record and hit error. It's a simple fix, but one that was fun to find in its completeness. :-) Even though you've told it what to do for a primary key, a MySQL table requires a gentle nudge to actually generate that new key value. Two things are needed to make the magic happen. First, you need to ensure the following annotation is in place in your Java entity classes: @GeneratedValue(strategy = GenerationType.IDENTITY) All well and good, but the real key is this: in your controller class(es), you'll have a create() function that looks something like this, minus the comment line and the setId() call in bold red type:     public String create() {         try {             // Assign 0 to ID for MySQL to properly auto_increment the primary key.             current.setId(0);             getFacade().create(current);             JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("CategoryCreated"));             return prepareCreate();         } catch (Exception e) {             JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));             return null;         }     } Setting the current object's primary key attribute to zero (0) prior to saving it tells MySQL to get the next available value and assign it to that record's key field. Short and simple…but not inherently obvious if you've never used that particular combination of NetBeans/JSF/MySQL before. Hope this helps! All the best, Mark

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• How Can I Safely Destroy Sensitive Data CDs/DVDs?

  - by Jason Fitzpatrick

  You have a pile of DVDs with sensitive information on them and you need to safely and effectively dispose of them so no data recovery is possible. What’s the most safe and efficient way to get the job done? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader HaLaBi wants to know how he can safely destroy CDs and DVDs with personal data on them: I have old CDs/DVDs which have some backups, these backups have some work and personal files. I always had problems when I needed to physically destroy them to make sure no one will reuse them. Breaking them is dangerous, pieces could fly fast and may cause harm. Scratching them badly is what I always do but it takes long time and I managed to read some of the data in the scratched CDs/DVDs. What’s the way to physically destroy a CD/DVD safely? How should he approach the problem? The Answer SuperUser contributor Journeyman Geek offers a practical solution coupled with a slightly mad-scientist solution: The proper way is to get yourself a shredder that also handles cds – look online for cd shredders. This is the right option if you end up doing this routinely. I don’t do this very often – For small scale destruction I favour a pair of tin snips – they have enough force to cut through a cd, yet are blunt enough to cause small cracks along the sheer line. Kitchen shears with one serrated side work well too. You want to damage the data layer along with shearing along the plastic, and these work magnificently. Do it in a bag, cause this generates sparkly bits. There’s also the fun, and probably dangerous way – find yourself an old microwave, and microwave them. I would suggest doing this in a well ventilated area of course, and not using your mother’s good microwave. There’s a lot of videos of this on YouTube – such as this (who’s done this in a kitchen… and using his mom’s microwave). This results in a very much destroyed cd in every respect. If I was an evil hacker mastermind, this is what I’d do. The other options are better for the rest of us. Another contributor, Keltari, notes that the only safe (and DoD approved) way to dispose of data is total destruction: The answer by Journeyman Geek is good enough for almost everything. But oddly, that common phrase “Good enough for government work” does not apply – depending on which part of the government. It is technically possible to recover data from shredded/broken/etc CDs and DVDs. If you have a microscope handy, put the disc in it and you can see the pits. The disc can be reassembled and the data can be reconstructed — minus the data that was physically destroyed. So why not just pulverize the disc into dust? Or burn it to a crisp? While technically, that would completely eliminate the data, it leaves no record of the disc having existed. And in some places, like DoD and other secure facilities, the data needs to be destroyed, but the disc needs to exist. If there is a security audit, the disc can be pulled to show it has been destroyed. So how can a disc exist, yet be destroyed? Well, the most common method is grinding the disc down to destroy the data, yet keep the label surface of the disc intact. Basically, it’s no different than using sandpaper on the writable side, till the data is gone. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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• Oracle Romania Summer School

  - by Maria Sandu

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 What would you say about a Summer School within a corporation where you can learn, play and practice? You might think that this is something usually uncommon for a company and you would be right. However, Oracle’s main value being innovation, we came up with a new project for Romanian students and graduates. We organised Oracle Summer School , offering them the opportunity to develop their soft skills and gain valuable business knowledge and exposure. How was Oracle Summer School programme organised? We focused on students and graduates’ needs and combined business experience with training and practice. The twenty four participants had different backgrounds, being interested in Software, Hardware, Finance, Marketing or other areas. The programme fulfilled each of these needs, bringing them in contact with Specialists and Managers. The first two weeks were dedicated to the company visits, business presentations and networking. The participants got an insight about employees’ activities and projects. Storytelling was also part of the program and people from different departments spent a couple of hours with the participants, sharing their experiences, knowledge and interesting stories. The Recruitment team delivered a training about the job interview skills in order to make the participants feel better prepared for a Recruitment process. The second module consisted of two weeks of Soft Skills trainings delivered by professional trainers from different departments. The participants gained useful insight on the competencies required within a business environment. The evenings were dedicated to social activities and it not very long until they started feel part of a team. The third module will take place at the end of September and will put the participants in contact with senior people from the business who will become their Mentors. What do the participants say about Oracle Summer School? “ As a fresh computer science graduate, Oracle Summer School gave me the opportunity of finding what are the technical and nontechnical skills required in a large multinational company. It was a great way of seeing how the theoretical knowledge I received during college is applied in real-life scenarios and what skills I still need to develop. “  (Cosmin Radu) “ When arriving at Oracle I had high expectations, but did not know exactly what was going to unfold because of the program's lack of precedence. Right after the first day, my feedback outgrew the initial forecast and the following weeks continued to build upon it. I had the pleasure to acquaint with brilliant people. The program was outlined on various profiles, delivering a comprehensive experience. It was very engaging, informative and nevertheless fun. “ (Vlad Manciu) „ Oracle Summer School is by far the best summer school that I have ever attended. For me it has been a great experience so far, because I’ve learned not only how to use soft skills in a corporate environment, but I’ve learned a great deal about myself as well. However, the most valuable asset of this 3-week period were the people that I’ve met: great individuals and great professionals, whom I really grew fond of.” (Alexandru Purcarea) “Applying to Oracle Summer School has been the best decision I took in regard to how to spend my summer holiday. I had the chance to do job shadowing at some of the departments I was interested in and I attended great trainings on various subjects such as time management and emotional intelligence. Moreover, I made friends with the other participants and we enjoyed going out together after “classes”.(Andreea Tudor) If you are interested in joining our team and attending our events please follow us on https://campus.oracle.com/campus/HR/emea_main.html /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-ascii- mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi- mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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• Server hung with "blocked for more than 120 seconds", diskless

  - by alterpub

  I have server which hung every 2-5 days. dmesg show following situation: kernel: [490894.231753] INFO: task munin-html:10187 blocked for more than 120 seconds. kernel: [490894.231799] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: [490894.231843] munin-html D 0000000000000000 0 10187 9796 0x00000000 kernel: [490894.231878] ffff88063174b968 0000000000000082 ffff88063174b8d8 0000000000015b80 kernel: [490894.231930] ffff88063174bfd8 0000000000015b80 ffff88063174bfd8 ffff88062fe644d0 kernel: [490894.231982] 0000000000015b80 0000000000015b80 ffff88063174bfd8 0000000000015b80 kernel: [490894.232033] Call Trace: kernel: [490894.232059] [<ffffffff8117fce0>] ? sync_buffer+0x0/0x50 kernel: [490894.232089] [<ffffffff815a1f13>] io_schedule+0x73/0xc0 kernel: [490894.232115] [<ffffffff8117fd25>] sync_buffer+0x45/0x50 kernel: [490894.232143] [<ffffffff815a258f>] __wait_on_bit+0x5f/0x90 kernel: [490894.232170] [<ffffffff8117fce0>] ? sync_buffer+0x0/0x50 kernel: [490894.232197] [<ffffffff815a2638>] out_of_line_wait_on_bit+0x78/0x90 kernel: [490894.232227] [<ffffffff81080250>] ? wake_bit_function+0x0/0x40 kernel: [490894.232255] [<ffffffff8117fcd6>] __wait_on_buffer+0x26/0x30 kernel: [490894.232288] [<ffffffffa00131be>] squashfs_read_data+0x1be/0x520 [squashfs] kernel: [490894.232320] [<ffffffff8114f0f1>] ? __mem_cgroup_try_charge+0x71/0x450 kernel: [490894.232350] [<ffffffffa0013963>] squashfs_cache_get+0x1c3/0x320 [squashfs] kernel: [490894.232381] [<ffffffffa00136eb>] ? squashfs_copy_data+0x10b/0x130 [squashfs] kernel: [490894.232426] [<ffffffff815a3dbe>] ? _raw_spin_lock+0xe/0x20 kernel: [490894.232454] [<ffffffffa0013b68>] ? squashfs_read_metadata+0x48/0xf0 [squashfs] kernel: [490894.232499] [<ffffffffa0013ae1>] squashfs_get_datablock+0x21/0x30 [squashfs] kernel: [490894.232544] [<ffffffffa0015026>] squashfs_readpage+0x436/0x4a0 [squashfs] kernel: [490894.232575] [<ffffffff8111a375>] ? __inc_zone_page_state+0x35/0x40 kernel: [490894.232606] [<ffffffff8110d072>] __do_page_cache_readahead+0x172/0x210 kernel: [490894.232636] [<ffffffff8110d131>] ra_submit+0x21/0x30 kernel: [490894.232662] [<ffffffff811045f3>] filemap_fault+0x3f3/0x450 kernel: [490894.232691] [<ffffffff812bd156>] ? prio_tree_insert+0x256/0x2b0 kernel: [490894.232726] [<ffffffffa009225d>] aufs_fault+0x11d/0x170 [aufs] kernel: [490894.232755] [<ffffffff8111f6d4>] __do_fault+0x54/0x560 kernel: [490894.232782] [<ffffffff81122f39>] handle_mm_fault+0x1b9/0x440 kernel: [490894.232811] [<ffffffff811286f5>] ? do_mmap_pgoff+0x335/0x380 kernel: [490894.232840] [<ffffffff815a7af5>] do_page_fault+0x125/0x350 kernel: [490894.232867] [<ffffffff815a4675>] page_fault+0x25/0x30 Os info cat /etc/issue.net Ubuntu 10.04.2 LTS uname -a Linux Shard1Host3 2.6.35-32-server #68~lucid1-Ubuntu SMP Wed Mar 28 18:33:00 UTC 2012 x86_64 GNU/Linux This system load via ltsp and hasn't harddrives also it has a lot of memory 24Gb. free -m total used free shared buffers cached Mem: 24152 17090 7061 0 50 494 -/+ buffers/cache: 16545 7607 Swap: 0 0 0 I put vmstat info here but I think it won't give results after reboot vmstat 1 30 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 7231156 52196 506400 0 0 0 0 172 143 7 0 92 0 1 0 0 7231024 52196 506400 0 0 0 0 7859 16233 5 0 94 0 0 0 0 7231024 52196 506400 0 0 0 0 7870 16446 2 0 98 0 0 0 0 7230900 52196 506400 0 0 0 0 7308 15661 5 0 95 0 0 0 0 7231100 52196 506400 0 0 0 0 7960 16543 6 0 94 0 0 0 0 7231100 52196 506400 0 0 0 0 7542 16047 5 1 94 0 3 0 0 7231100 52196 506400 0 0 0 0 7709 16621 3 0 96 0 0 0 0 7231220 52196 506400 0 0 0 0 7857 16552 4 0 96 0 0 0 0 7231220 52196 506400 0 0 0 0 7192 15491 6 0 94 0 0 0 0 7231220 52196 506400 0 0 0 0 7423 15792 5 1 94 0 1 0 0 7231260 52196 506404 0 0 0 0 7686 16296 2 0 98 0 0 0 0 7231260 52196 506404 0 0 0 0 6976 15183 5 0 95 0 0 0 0 7231260 52196 506404 0 0 0 0 7303 15600 4 0 95 0 0 0 0 7231320 52196 506404 0 0 0 0 7967 16241 1 0 98 0 0 0 0 7231444 52196 506404 0 0 0 0 6948 15113 6 0 94 0 0 0 0 7231444 52196 506404 0 0 0 0 7931 16181 6 0 94 0 1 0 0 7231516 52196 506404 0 0 0 0 7715 15829 6 0 94 0 0 0 0 7231516 52196 506404 0 0 0 0 7771 16036 2 0 97 0 0 0 0 7231268 52196 506404 0 0 0 0 7782 16202 6 0 94 0 1 0 0 7231212 52196 506404 0 0 0 0 7457 15622 4 0 96 0 0 0 0 7231212 52196 506404 0 0 0 0 7573 16045 2 0 98 0 2 0 0 7231216 52196 506404 0 0 0 0 7689 16076 6 0 94 0 0 0 0 7231424 52196 506404 0 0 0 0 7429 15650 4 0 95 0 3 0 0 7231424 52196 506404 0 0 0 0 7534 16168 3 0 97 0 1 0 0 7230548 52196 506404 0 0 0 0 8559 15926 7 1 92 0 0 0 0 7230672 52196 506404 0 0 0 0 7720 15905 2 0 98 0 0 0 0 7230548 52196 506404 0 0 0 0 7677 16313 5 0 95 0 1 0 0 7230676 52196 506404 0 0 0 0 7209 15432 5 0 95 0 0 0 0 7230800 52196 506404 0 0 0 0 7522 15861 2 0 98 0 0 0 0 7230552 52196 506404 0 0 0 0 7760 16661 5 0 95 0 In the munin(monitoring system) graphs I see(before server hung): Disk(nbd0) IOs per device: read: 289m but avg by week 2.09m Disk(nbd0) throughput per device: read: 4.73k but avg by week 108.76 Disk(nbd0) utilization per device: 100% but avg by week 1.2% Eth0 traffic was low: in/out only 2Mbps Number of threads increased to 566 usually 392 Fork rate 1.08 but usually 2.82 VMStat(processes state) Increased to 17.77(from 0 as far as I could see in the graph) CPU usage iowait 880.46% when usually 6.67% It'll be great if somebody help me to understand what's up.

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• Stumbling Through: Visual Studio 2010 (Part II)

  I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Agile Testing Days 2012 – My First Conference!

  - by Chris George

  I’d like to give you a bit of background first… so please bear with me! In 1996, whilst studying for my final year of my degree, I applied for a job as a C++ Developer at a small software house in Hertfordshire  After bodging up the technical part of the interview I didn’t get the job, but was offered a position as a QA Engineer instead. The role sounded intriguing and the pay was pretty good so in the absence of anything else I took it. Here began my career in the world of software testing! Back then, testing/QA was often an afterthought, something that was bolted on to the development process and very much a second class citizen. Test automation was rare, and tools were basic or non-existent! The internet was just starting to take off, and whilst there might have been testing communities and resources, we were certainly not exposed to any of them. After 8 years I moved to another small company, and again didn’t find myself exposed to any of the changes that were happening in the industry. It wasn’t until I joined Red Gate in 2008 that my view of testing and software development as a whole started to expand. But it took a further 4 years for my view of testing to be totally blown open, and so the story really begins… In May 2012 I was fortunate to land the role of Head of Test Engineering. Soon after, I received an email with details for the “Agile Testi However, in my new role, I decided that it was time to bite the bullet and at least go to one conference. Perhaps I could get some new ideas to supplement and support some of the ideas I already had.ng Days” conference in Potsdam, Germany. I looked over the suggested programme and some of the talks peeked my interest. For numerous reasons I’d shied away from attending conferences in the past, one of the main ones being that I didn’t see much benefit in attending loads of talks when I could just read about stuff like that on the internet. So, on the 18th November 2012, myself and three other Red Gaters boarded a plane at Heathrow bound for Potsdam, Germany to attend Agile Testing Days 2012. Tutorial Day – “Software Testing Reloaded” We chose to do the tutorials on the 19th, I chose the one titled “Software Testing Reloaded – So you wanna actually DO something? We’ve got just the workshop for you. Now with even less powerpoint!”. With such a concise and serious title I just had to see what it was about! I nervously entered the room to be greeted by tables, chairs etc all over the place, not set out and frankly in one hell of a mess! There were a few people in there playing a game with dice. Okaaaay… this is going to be a long day! Actually the dice game was an exercise in deduction and simplification… I found it very interesting and is certainly something I’ll be using at work as a training exercise! (I won’t explain the game here cause I don’t want to let the cat out of the bag…) The tutorial consisted of several games, exploring different aspects of testing. They were all practical yet required a fair amount of thin king. Matt Heusser and Pete Walen were running the tutorial, and presented it in a very relaxed and light-hearted manner. It was really my first experience of working in small teams with testers from very different backgrounds, and it was really enjoyable. Matt & Pete were very approachable and offered advice where required whilst still making you work for the answers! One of the tasks was to devise several strategies for testing some electronic dice. The premise was that a Vegas casino wanted to use the dice to appeal to the twenty-somethings interested in tech, but needed assurance that they were as reliable and random as traditional dice. This was a very interesting and challenging exercise that forced us to challenge various assumptions, determine/clarify requirements but most of all it was frustrating because the dice made a very very irritating beeping noise. Multiple that by at least 12 dice and I was dreaming about them all that night!! Some of the main takeaways that were brilliantly demonstrated through the games were not to make assumptions, challenge requirements, and have fun testing! The tutorial lasted the whole day, but to be honest the day went very quickly! My introduction into the conference experience started very well indeed, and I would talk to both Matt and Pete several times during the 4 days. Days 1,2 & 3 will be coming soon…  

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• Yes, I did it - Skydiving in Mauritius

  Finally, I did it or better said we did it. Already back in November last year I saw the big billboard advertisement of Skydive Austral Mauritius near Caudan Waterfront in Port Louis and decided for myself that this is going to be the perfect birthday gift for my wife. Simply out of curiosity I would join her tandem jump with a second instructor. Due to her pregnancy of our son I had to be patient... But then finally, her birthday had arrived and on our midnight celebration session I showed her her netbook with the website preloaded. Actually, it was the "perfect" timing... Recovery from her cesarean is fine, local weather conditions are gorgious and the children were under surveillance of my mum - spending her annual holidays on the island. So, after late wake-up in the morning, we packed our stuff and off we went. According to Google Maps direction indication we had to drive for roughly 50km (only) but traffic here in Mauritius is always challenging. The dropzone is at the Zone Industrielle Mon Loisir Sugar Estate near Riviere du Rempart at the northern east coast. Anyways, we were not in a hurry and arrived there shortly after noon. The access road to the airfield are just small down-driven paths through sugar cane fields and according to our daughter "it's bumpy!". True true true... The facilities at Skydive Austral Mauritius are complete except for food. Enough space for parking, easy handling at the reception and a lot to see for the kids. There's even a big terrace with several sets of tables and chairs, small bar for soft drinks, strictly non-alcoholic. The team over there is all welcoming and warm-hearthy! Having the kids with us was no issue at all. Quite the opposite, our daugther was allowed to discover a lot of things than we adults did. Even visiting the small air plane was on the menu for her. Really great stuff! While waiting for our turn we enjoyed watching other people getting ready in the jump gear, taking off with the Cessna, and finally coming back down on the tandem parachute. Actually, the different expressions on their faces was one of the best parts while waiting. Great mental preparation as my wife was getting more anxious about her first jump... {loadposition content_adsense} First, we got some information about the procedures on the plane about how to get seated, tight up with our instructors and how to get ready for the jump off the plane as soon as we arrive the height of 10.000 ft. All well explained and easy to understand after all.Next, we met with our jumpers Chris and Lee aka "Rasta" to get dressed and ready for take-off. Those guys are really cool and relaxed for their job. From that point on, the DVD session / recording for my wife's birthday started and we really had a lot of fun... The difference between that small Cessna and a commercial flight with an Airbus or a Boeing is astronomic! The climb up to 10.000 ft took us roughly 25 minutes and we enjoyed the magnificent view over the turquoise lagunes near Poste de Flacq, Lafayette and Isle d'Ambre on the north-east coast. After flying through the clouds we sun-bathed and looked over "iced-sugar covered" Mauritius. You might have a look at the picture gallery of Skydive Mauritius for better imagination. The moment of truth, or better said, point of no return came after approximately 25 minutes. The door opens, moving into position on the side on top of the wheel and... out! Back flip and free fall! Slight turns and Wooooohooooo! through the clouds... It so amazing and breath-taking! So undescribable! You have to experience this yourself! Some seconds later the parachute opened and we glided smoothly with some turns and spins back down to the dropzone. The rest of the family could hear and see us soon and the landing was easy going. We never had any doubts or fear about our instructors. They did a great job and we are looking forward to book our next job. I might even consider to follow educational classes on skydiving and earn a license. By the way, feel free to get in touch with Skydive Austral Mauritius. Either via contact details on their website or tweeting a little bit with them. Follow the tweets of Chris and fellows on SkydiveAustral.

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• Airline mess - what a journey

  - by Mike Dietrich

  What a day, what a journey ... Flew this noon from Munich to Zuerich for catch my ongoing flight to San Francisco with Swiss. And that day did start very well as Lufthansa messed up the connection flight by 42 minutes for a 35 minute flight. And as I was obviously the only passenger connection to San Francisco nobody picked me up at the airplane to bring me directly to my connection as Swiss did for the 8 passengers connection to Miami. So I missed my flight. What a start - and many thanks to Lufthansa. I was not the only one missing a connection as Lufthansa/Swiss had canceled the flight before due to "technical problems". In Zuerich Swiss did rebook me via Frankfurt with Lufthansa to board a United Airlines flight to San Francisco. "Ouch" I thought. I had my share of experience with United already as they've messed up my luggage on the way to San Francisco some years ago and it took them five (!!!) days to fly my bag over and deliver it. But actually it was the only option today. So I said "Yes". A big mistake as I've learned later on. The Frankfurt flight was delayed as well "due to a late incoming aircraft". But there was plenty of time. And I went to the Swiss counter at the gate and let them check if my baggage is on that flight to Frankfurt. They've said "Yes". Boarding the plane with a delay of 45 minutes (the typical Lufthansa delay these days) I spotted my Rimowa trolley right next to the plane on the airfield. So I was sure that it will be send to Frankfurt. In Frankfurt I went to the United counter once it did open - had to go through the passport check they do for US flights as well - and they've said "Yes, your luggage is with us". Well ... Arriving in San Francisco with just a bit of a some minutes delay and a very fast immigration procedure I saw the first bags with Priority tags getting pushed to the baggage claim - but mine was not there. I did wait ... and wait ... and wait. Well, thanks United, you did it again!!! I flew twice in the past years United Airlines - and in both cases they've messed up my luggage on the way to San Francisco. How lovely is that ... Now the real fun started again as the lady at the "Lost and Found" counter for luggage spotted my luggage in her system in Zuerich - and told me it's supposed to be sent with LH1191 to Frankfurt on Sept 27. But this was yesterday in Europe - it's already Sept 28 - and I saw my luggage in front of the airplane. So I'd suppose it's in Frankfurt already. But what could she do? Nothing but doing the awful paperwork. And "No Mr Dietrich, we don't call international numbers". Thank you, United. Next time I'll try to get a contract for a US land line in advance. They can't even tell you which plane will bring your luggage. It may be tomorrow with UA flight arriving around 4pm in SFO. I'm looking forward to some hours in the wonderful United Airlines call center waiting line. Last time I did spend 60-90 minutes every day until I got my luggage. If it takes again that long then OOW will be over by then. I love airline travel - and especially with United Airlines. And by the way ... they gave us these nice fancy packages during the flight:  That looks good - what's in that box??? Yes, really ... a bag of potato chips. Pure fat - very healthy.  I doubt that I'll ever fly United Airlines again!!!

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• Think before you animate

  - by David Paquette

  Animations are becoming more and more common in our applications.  With technologies like WPF, Silverlight and jQuery, animations are becoming easier for developers to use (and abuse).  When used properly, animation can augment the user experience.  When used improperly, animation can degrade the user experience.  Sometimes, the differences can be very subtle. I have recently made use of animations in a few projects and I very quickly realized how easy it is to abuse animation techniques.  Here are a few things I have learned along the way. 1) Don’t animate for the sake of animating We’ve all seen the PowerPoint slides with annoying slide transitions that animate 20 different ways.  It’s distracting and tacky.  The same holds true for your application.  While animations are fun and becoming easy to implement, resist the urge to use the technology just because you think the technology is amazing.   2) Animations should (and do) have meaning I recently built a simple Windows Phone 7 (WP7) application, Steeped (download it here).  The application has 2 pages.  The first page lists a number of tea types.  When the user taps on one of the tea types, the application navigates to the second page with information about that tea type and some options for the user to choose from.       One of the last things I did before submitting Steeped to the marketplace was add a page transition between the 2 pages.  I choose the Slide / Fade Out transition.  When the user selects a tea type, the main page slides to the left and fades out.  At the same time, the details page slides in from the right and fades in.  I tested it and thought it looked great so I submitted the app.  A few days later, I asked a friend to try the app.  He selected a tea type, and I was a little surprised by how he used the app.  When he wanted to navigate back to the main page, instead of pressing the back button on the phone, he tried to use a swiping gesture.  Of course, the swiping gesture did nothing because I had not implemented that feature.  After thinking about it for a while, I realized that the page transition I had chosen implied a particular behaviour.  As a user, if an action I perform causes an item (in this case the page) to move, then my expectation is that I should be able to move it back.  I have since added logic to handle the swipe gesture and I think the app flows much better now. When using animation, it pays to ask yourself:  What story does this animation tell my users?   3) Watch the replay Some animations might seem great initially but can get annoying over time.  When you use an animation in your application, make sure you try using it over and over again to make sure it doesn’t get annoying.  When I add an animation, I try watch it at least 25 times in a row.  After watching the animation repeatedly, I can make a more informed decision whether or not I should keep the animation.  Often, I end up shortening the length of the animations.   4) Don’t get in the users way An animation should never slow the user down.  When implemented properly, an animation can give a perceived bump in performance.  A good example of this is a the page transitions in most of the built in apps on WP7.  Obviously, these page animations don’t make the phone any faster, but they do provide a more responsive user experience.  Why?  Because most of the animations begin as soon as the user has performed some action.  The destination page might not be fully loaded yet, but the system responded immediately to user action, giving the impression that the system is more responsive.  If the user did not see anything happen until after the destination page was fully loaded, the application would feel clumsy and slow.  Also, it is important to make sure the animation does not degrade the performance (or perceived performance) of the application.   Jut a few things to consider when using animations.  As is the case with many technologies, we often learn how to misuse it before we learn how to use it effectively.

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• EM CLI, diving in and beyond!

  - by Maureen Byrne

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Doing more in less time… Isn’t that what we all strive to do? With this in mind, I put together two screen watches on Oracle Enterprise Manager 12c command line interface, or EM CLI as it is also known. There is a wealth of information on any topic that you choose to read about, from manual pages to coding documents…might I even say blog posts? In our busy lives it is so nice to just sit back with a short video, watch and learn enough to dive in. Doing more in less time, is the essence of EM CLI. It enables you to script fundamental and complex administrative tasks in an elegant way, thanks to the Jython scripting language. Repetitive tasks can be scripted and reused again and again. Sure, a Graphical User Interface provides a more intuitive step by step approach to tasks, and it provides a way of quickly becoming familiar with a product and its many features, and it is definitely the way to go when viewing performance data and historical trending…but for repetitive and complex tasks, scripting is the way to go! Lets us take the everyday task of creating an administrator. Using EM CLI in interactive mode the command could look like this.. emcli>create_user(name='jan.doe', type='EXTERNAL_USER') This command creates an administrator called jan.doe which is an externally authenticated user, possibly LDAP or SSO, defined by the EXTERNAL_USER tag. The create_user procedure takes many arguments; see the documentation for more information. Now, where EM CLI really shines and shows power is in creating multiple users. Regardless of the number, tens or thousands, the effort is the same. With the use of a standard programming construct, a loop, you can place your create_user() procedure within it. Using a loop allows you to iterate through a previously created list, creating new users until the list is complete. Using EM CLI in Script mode, your Jython loop would look something like this… for user in list_of_users:       create_user(name=user, expire=’true’, password=’welcome123’) This Jython code snippet iterates through a previously defined list of names, list_of_users, and iterates through the list, taking each name, user in this case, and creates an administrator sets the password to welcome123, but forces the user to reset it when they first login. This is only one of over four hundred procedures created to expose Oracle Enterprise Manager 12c functionality in a powerful and programmatic way. It is a few months since we released EM CLI with scripting option. We are seeing many users adapt to this fun and powerful way of using Oracle Enterprise Manager 12c. What are the first steps? Watch these screen watches, and dive in. The first screen watch steps you through where and how to download and install and how to run your first few commands. The Second screen watch steps you through a few scripts. Next time, I am going to show you the basic building blocks to writing a Jython script to perform Oracle Enterprise Manager 12c administrative tasks. Join this growing group of EM CLI users…. Dive in! Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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• setting up Ubuntu 10.10 as paravirtualized guest in Xen on RHEL5 host - what kernel?

  - by kostmo

  I've discovered the tool ubuntu-vm-builder, which I've installed and then invoked on an Ubuntu workstation as: sudo vmbuilder xen ubuntu --suite maverick --flavour virtual --arch amd64 --mem=512 --rootsize 8192 This workstation is not the intended target host of the virtual machine, however; I would like to host the guest on a Red Hat Enterprise Linux 5 machine that is running Xen 3.0.3. The output of this command appears to be a folder named ubuntu-xen containing three files: tmpXXXXXX, a very large file which I assume is the root partition image tmpYYYYYY, a somewhat large file which I assume is the swap partition image xen.conf, a text file I have copied the xen.conf file to the RHEL server's /etc/xen directory under the new name newvm, adjusting the paths of tempXXXXXX and tempYYYYYYin the file after also copying them from my local workstation to the RHEL server. When I launch the Virtual Machine Manager virt-manager, I can see the newvm virtual machine listed underneath the Dom0 machine. When I try to start newvm, I get the error: Error starting domain: virDomainCreate() failed POST operation failed: (xend.err 'Error creating domain: Kernel image does not exist: None') Indeed, there exists an entry kernel = 'None' in the xen.conf file. How do I find out what the path of the kernel should be? Is this path supposed to be to a kernel stored on the local filesystem of the RHEL5 host, or is it supposed to be a path inside the guest image? I see that the vmbuilder command provides for a --xen-kernel option, along with a --xen-ramdisk option, but I'm not sure what to use for either. I think I should be able to get this to work, since Ubuntu is said to be supported as a Xen guest, even though the Xen 4.0.1 docs state support for only a limited set of distributions, Ubuntu excluded. Update 1 When running vmbuilder on my local workstation, I did observe an output line saying: Calling hook: install_kernel and later, output lines saying: update-initramfs: Generating /boot/initrd.img-2.6.35-23-virtual [...] run-parts: executing /etc/kernel/postinst.d/initramfs-tools 2.6.35-23-virtual /boot/vmlinuz-2.6.35-23-virtual So in the xen.conf file, I tried setting the lines: kernel = '/boot/vmlinuz-2.6.35-23-virtual' ramdisk = '/boot/initrd.img-2.6.35-23-virtual' When trying to start the VM, I got an error similar to last time: Error starting domain: virDomainCreate() failed POST operation failed: (xend.err 'Error creating domain: Kernel image does not exist: /boot/vmlinuz-2.6.35-23-virtual') This makes me think that the RHEL5 machine is looking for local files, rather than a file within the binary guest disk image. After running sudo updatedb on my workstation, neither of those files were found. If the vmbuilder tool had tried to install them, it must have failed. Update 2 I was able to extract the kernel and initrd images from the guest disk binary by mounting it: mkdir mnt_tmp sudo mount ubuntu-xen/tmpXXXXXX mnt_tmp/ -o loop cp mnt_tmp/boot/vmlinuz-2.6.35-23-virtual virtual_kernel_ubuntu cp mnt_tmp/boot/initrd.img-2.6.35-23-virtual virtual_initrd_ubuntu These two files I copied to the RHEL5 server, and edited the xen.conf file to point to them as kernel and ramdisk. With this done, I could "run" the newvm virtual machine from within virt-manager, but was met with the message Console Not Configured For Guest when I double clicked the entry to open the Virtual Machine Console. As suggested by a forum, I then added the line vfb = [ 'type=vnc' ] to the configuration file, recreated the virtual machine (a ~10 min process), and this time got the message: Connecting to console for guest This remained indefinitely; after selecting View - Serial Console, I found a kernel panic: [5442621.272173] Kernel panic - not syncing: Attempted to kill the idle task! [5442621.272179] Pid: 0, comm: swapper Tainted: G D 2.6.35-23-virtual #41-Ubuntu [5442621.272184] Call Trace: [5442621.272191] [<ffffffff815a1b81>] panic+0x90/0x111 [5442621.272199] [<ffffffff810652ee>] do_exit+0x3be/0x3f0 [5442621.272204] [<ffffffff815a5e20>] oops_end+0xb0/0xf0 [5442621.272211] [<ffffffff8100ddeb>] die+0x5b/0x90 [5442621.272216] [<ffffffff815a56c4>] do_trap+0xc4/0x170 [5442621.272221] [<ffffffff8100ba35>] do_invalid_op+0x95/0xb0 [5442621.272227] [<ffffffff8130851c>] ? intel_idle+0xac/0x180 [5442621.272232] [<ffffffff810072bf>] ? xen_restore_fl_direct_end+0x0/0x1 [5442621.272239] [<ffffffff815a48fe>] ? _raw_spin_unlock_irqrestore+0x1e/0x30 [5442621.272247] [<ffffffff8108dfb7>] ? tick_broadcast_oneshot_control+0xc7/0x120 [5442621.272253] [<ffffffff8100ad5b>] invalid_op+0x1b/0x20 [5442621.272259] [<ffffffff8130851c>] ? intel_idle+0xac/0x180 [5442621.272264] [<ffffffff813084e0>] ? intel_idle+0x70/0x180 [5442621.272269] [<ffffffff810072bf>] ? xen_restore_fl_direct_end+0x0/0x1 [5442621.272275] [<ffffffff8148a147>] cpuidle_idle_call+0xa7/0x140 [5442621.272281] [<ffffffff81008d93>] cpu_idle+0xb3/0x110 [5442621.272286] [<ffffffff815873aa>] rest_init+0x8a/0x90 [5442621.272291] [<ffffffff81b04c9d>] start_kernel+0x387/0x390 [5442621.272297] [<ffffffff81b04341>] x86_64_start_reservations+0x12c/0x130 [5442621.272303] [<ffffffff81b08002>] xen_start_kernel+0x55d/0x561 Update 3 I tried an i386 architecture instead of amd64, but got the same kernel panic. Also, it seems the Virtual Machine Manager pays attention to the format of the filename of the kernel; for the same kernel binary, I tried simply naming it vmlinuz-virtual, which threw out an error box about an invalid kernel. When I named it vmlinuz-2.6.35-23-virtual, it did not throw the error, but it did still result in the kernel panic shortly thereafter.

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• xen domUs crashes or unavailability

  - by Rush

  I've xen server with 8 domU. Server is Xeon E31270 with 16gb ram. I think it is enough for 8 machines. Sometimes domU's crashes and i can't figure out the reason. After crash i can connect to console and there is somthing like this: Oct 8 22:20:49 server kernel: [30892.320780] lowmem_reserve[]: 0 0 0 0 Oct 8 22:20:49 server kernel: [30892.320790] Node 0 DMA: 10*4kB 3*8kB 13*16kB 10*32kB 7*64kB 3*128kB 2*256kB 2*512kB 1*1024kB 2*2048kB 0*4096kB = 8080kB Oct 8 22:20:49 server kernel: [30892.320817] Node 0 DMA32: 648*4kB 2*8kB 1*16kB 0*32kB 1*64kB 0*128kB 0*256kB 0*512kB 1*1024kB 1*2048kB 0*4096kB = 5760kB Oct 8 22:20:49 server kernel: [30892.320842] 1491 total pagecache pages Oct 8 22:20:49 server kernel: [30892.320847] 0 pages in swap cache Oct 8 22:20:49 server kernel: [30892.320852] Swap cache stats: add 0, delete 0, find 0/0 Oct 8 22:20:49 server kernel: [30892.320858] Free swap = 0kB Oct 8 22:20:49 server kernel: [30892.320862] Total swap = 0kB Oct 8 22:20:49 server kernel: [30892.324024] 524288 pages RAM Oct 8 22:20:49 server kernel: [30892.324024] 11010 pages reserved Oct 8 22:20:49 server kernel: [30892.324024] 424467 pages shared Oct 8 22:20:49 server kernel: [30892.324024] 503538 pages non-shared Oct 8 22:20:49 server kernel: [30892.330308] apache2 invoked oom-killer: gfp_mask=0x200da, order=0, oom_adj=0 Oct 8 22:20:49 server kernel: [30892.330322] apache2 cpuset=/ mems_allowed=0 Oct 8 22:20:49 server kernel: [30892.330330] Pid: 23938, comm: apache2 Not tainted 2.6.32-5-xen-amd64 #1 Oct 8 22:20:49 server kernel: [30892.330337] Call Trace: Oct 8 22:20:49 server kernel: [30892.330349] [<ffffffff810b7180>] ? oom_kill_process+0x7f/0x23f Oct 8 22:20:49 server kernel: [30892.330358] [<ffffffff810b76a4>] ? __out_of_memory+0x12a/0x141 Oct 8 22:20:49 server kernel: [30892.330367] [<ffffffff810b77fb>] ? out_of_memory+0x140/0x172 Oct 8 22:20:49 server kernel: [30892.330376] [<ffffffff810bb59c>] ? __alloc_pages_nodemask+0x4e5/0x5f5 Oct 8 22:20:49 server kernel: [30892.330385] [<ffffffff810cc224>] ? do_wp_page+0x386/0x707 Oct 8 22:20:49 server kernel: [30892.330395] [<ffffffff8100c3a5>] ? __raw_callee_save_xen_pud_val+0x11/0x1e Oct 8 22:20:49 server kernel: [30892.330404] [<ffffffff8100c369>] ? __raw_callee_save_xen_pmd_val+0x11/0x1e Oct 8 22:20:49 server kernel: [30892.330412] [<ffffffff810cdfc7>] ? handle_mm_fault+0x7aa/0x80f Oct 8 22:20:49 server kernel: [30892.330422] [<ffffffff8130f906>] ? do_page_fault+0x2e0/0x2fc Oct 8 22:20:49 server kernel: [30892.330433] [<ffffffff8130d7a5>] ? page_fault+0x25/0x30 Oct 8 22:20:49 server kernel: [30892.330439] Mem-Info: Oct 8 22:20:49 server kernel: [30892.330443] Node 0 DMA per-cpu: Oct 8 22:20:49 server kernel: [30892.330450] CPU 0: hi: 0, btch: 1 usd: 0 Oct 8 22:20:49 server kernel: [30892.330463] CPU 1: hi: 0, btch: 1 usd: 0 Oct 8 22:20:49 server kernel: [30892.330466] Node 0 DMA32 per-cpu: Oct 8 22:20:49 server kernel: [30892.330469] CPU 0: hi: 186, btch: 31 usd: 0 Oct 8 22:20:49 server kernel: [30892.330472] CPU 1: hi: 186, btch: 31 usd: 60 Oct 8 22:20:49 server kernel: [30892.330476] active_anon:342076 inactive_anon:115398 isolated_anon:0 Oct 8 22:20:49 server kernel: [30892.330477] active_file:268 inactive_file:481 isolated_file:0 Oct 8 22:20:49 server kernel: [30892.330477] unevictable:1125 dirty:2 writeback:13 unstable:0 Oct 8 22:20:49 server kernel: [30892.330478] free:3410 slab_reclaimable:1718 slab_unreclaimable:6946 Oct 8 22:20:49 server kernel: [30892.330478] mapped:899 shmem:113 pagetables:35697 bounce:0 Oct 8 22:20:49 server kernel: [30892.330502] Node 0 DMA free:8036kB min:32kB low:40kB high:48kB active_anon:1144kB inactive_anon:1268kB active_file:8kB inactive_file:8kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:11792kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:224kB kernel_stack:16kB pagetables:1228kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no Oct 8 22:20:49 server kernel: [30892.330518] lowmem_reserve[]: 0 2004 2004 2004 Oct 8 22:20:49 server kernel: [30892.330523] Node 0 DMA32 free:5604kB min:5708kB low:7132kB high:8560kB active_anon:1367160kB inactive_anon:460324kB active_file:1064kB inactive_file:1916kB unevictable:4500kB isolated(anon):0kB isolated(file):0kB present:2052320kB mlocked:4500kB dirty:8kB writeback:52kB mapped:3600kB shmem:452kB slab_reclaimable:6872kB slab_unreclaimable:27560kB kernel_stack:3528kB pagetables:141560kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:992 all_unreclaimable? no Oct 8 22:20:49 server kernel: [30892.330539] lowmem_reserve[]: 0 0 0 0 Oct 8 22:20:49 server kernel: [30892.330544] Node 0 DMA: 1*4kB 2*8kB 13*16kB 10*32kB 7*64kB 3*128kB 2*256kB 2*512kB 1*1024kB 2*2048kB 0*4096kB = 8036kB Oct 8 22:20:49 server kernel: [30892.330579] Node 0 DMA32: 609*4kB 2*8kB 1*16kB 0*32kB 1*64kB 0*128kB 0*256kB 0*512kB 1*1024kB 1*2048kB 0*4096kB = 5604kB Oct 8 22:20:49 server kernel: [30892.330605] 1522 total pagecache pages Oct 8 22:20:49 server kernel: [30892.330610] 0 pages in swap cache Oct 8 22:20:49 server kernel: [30892.330615] Swap cache stats: add 0, delete 0, find 0/0 Oct 8 22:20:49 server kernel: [30892.330621] Free swap = 0kB Oct 8 22:20:49 server kernel: [30892.330625] Total swap = 0kB Oct 8 22:20:49 server kernel: [30892.333018] 524288 pages RAM Oct 8 22:20:49 server kernel: [30892.333018] 11010 pages reserved Oct 8 22:20:49 server kernel: [30892.333018] 424367 pages shared Oct 8 22:20:49 server kernel: [30892.333018] 503658 pages non-shared Seems like there isn't enough memory for this domU. But there is no any memory problems reported in munin monitoring: As you see system uses around 0.2G and 1G is available. So my question is: Is it xen specific problem, that real memory usage and memory usage that shows munin are different (I've never seen such problems oh real hardware machines)? Or maybe it is just monitoring problem, that can't catch moment when there is unusual high load and domU go down? And how I can to defeat this problem? it is really annoying to catch messages in e-mail that domU went down. Btw, such situation was when domU had 2G memory.

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• Migrating Virtual Iron guest to Oracle VM 3.x

  - by scoter

  As stated on the official site, Oracle in 2009, acquired a provider of server virtualization management software named Virtual Iron; you can find all the acquisition details at this link. Into the FAQ on the official site you can also view that, for the future, Oracle plans to fully integrate Virtual Iron technology into Oracle VM products, and any enhancements will be delivered as a part of the combined solution; this is what is going on with Oracle VM 3.x. So, customers started asking us to migrate Virtual Iron guests to Oracle VM. IMPORTANT: This procedure needs a dedicated OVM-Server with no-guests running on top; be careful while execute this procedure on production environments. In these little steps you will find how-to migrate, as fast as possible, your guests between VI ( Virtual Iron ) and Oracle VM; keep in mind that OracleVM has a built-in P2V utility ( Official Documentation )  that you can use to migrate guests between VI and Oracle VM. Concepts: VI repositories.  On VI we have the same "repository" concept as in Oracle VM; the difference between these two products is that VI use a raw-lun as repository ( instead of using ocfs2 and its capabilities, like ref-links ). The VI "raw-lun" repository, with a pure operating-system perspective, may be presented as in this picture: Infact on this "raw-lun" VI create an LVM2 volume-group. The VI "raw-lun" repository, with an hypervisor perspective, may be presented as in this picture: So, the relationships are: LVM2-Volume-Group <-> VI Repository LVM2-Logical-Volume <-> VI guest virtual-disk The first step is to present the VI repository ( raw-lun ) to your dedicated OVM-Server. Prepare dedicated OVM-Server On the OVM-Server ( OVS ) you need to discover new lun and, after that, discover volume-group and logical-volumes containted in VI repository; due to default OVS configuration you need to edit lvm2 configuration file: /etc/lvm/lvm.conf     # By default for OVS we restrict every block device:     # filter = [ "r/.*/" ] and comment the line starting with "filter" as above. Now you have to discover the raw-lun presented and, next, activate volume-group and logical-volumes: #!/bin/bash for HOST in `ls /sys/class/scsi_host`;do echo '- - -' > /sys/class/scsi_host/$HOST/scan; done CPATH=`pwd` cd /dev for DEVICE in `ls sd[a-z] sd?[a-z]`;do echo '1' > /sys/block/$DEVICE/device/rescan; done cd $CPATH cd /dev/mapper for PARTITION in `ls *[a-z] *?[a-z]`;do partprobe /dev/mapper/$PARTITION; done cd $CPATH vgchange -a yAfter that you will see a new device:[root@ovs01 ~]# cd /dev/6000F4B00000000000210135bef64994[root@ovs01 6000F4B00000000000210135bef64994]# ls -l 6000F4B0000000000061013* lrwxrwxrwx 1 root root 77 Oct 29 10:50 6000F4B00000000000610135c3a0b8cb -> /dev/mapper/6000F4B00000000000210135bef64994-6000F4B00000000000610135c3a0b8cb By your OVM-Manager create a guest server with the same definition as on VI:same core number as VI source guestsame memory as VI source guestsame number of disks as VI source guest ( you can create OVS virtual disk with a small size of 1GB because the "clone" will, eventually, extend the size of your new virtual disks )Summarizing:source-virtual-disk path ( VI ):/dev/mapper/6000F4B00000000000210135bef64994-6000F4B00000000000610135c3a0b8cbdest-virtual-disk path ( OVS ):/OVS/Repositories/0004fb00000300006cfeb81c12f12f00/VirtualDisks/0004fb000012000055e0fc4c5c8a35ee.img ** ** = to identify your virtual disk you have verify its name under the "vm.cfg" file of your new guest.Clone VI virtual-disk to OVS virtual-diskdd if=/dev/mapper/6000F4B00000000000210135bef64994-6000F4B00000000000610135c3a0b8cb of=/OVS/Repositories/0004fb00000300006cfeb81c12f12f00/VirtualDisks/0004fb000012000055e0fc4c5c8a35ee.img Clean unsupported parameters and changes on OVS.1. Restore original /etc/lvm/lvm.conf    # By default for OVS we restrict every block device:     filter = [ "r/.*/" ]    and uncomment the line starting with "filter" as above.2. Force-stop lvm2-monitor service  # service lvm2-monitor force-stop 3. Restore original /etc/lvm directories ( archive, backup and cache )  # cd /etc/lvm  # rm -fr archive backup cache; mkdir archive backup cache4. Reboot OVSRefresh OVS repository and start your guest.By OracleVM Manager refresh your repository:By OracleVM Manager start your "migrated" guest: Comments and corrections are welcome.  Simon COTER 

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• Managing text-maps in a 2D array on to be painted on HTML5 Canvas

  - by weka

  So, I'm making a HTML5 RPG just for fun. The map is a <canvas> (512px width, 352px height | 16 tiles across, 11 tiles top to bottom). I want to know if there's a more efficient way to paint the <canvas>. Here's how I have it right now. How tiles are loaded and painted on map The map is being painted by tiles (32x32) using the Image() piece. The image files are loaded through a simple for loop and put into an array called tiles[] to be PAINTED on using drawImage(). First, we load the tiles... and here's how it's being done: // SET UP THE & DRAW THE MAP TILES tiles = []; var loadedImagesCount = 0; for (x = 0; x <= NUM_OF_TILES; x++) { var imageObj = new Image(); // new instance for each image imageObj.src = "js/tiles/t" + x + ".png"; imageObj.onload = function () { console.log("Added tile ... " + loadedImagesCount); loadedImagesCount++; if (loadedImagesCount == NUM_OF_TILES) { // Onces all tiles are loaded ... // We paint the map for (y = 0; y <= 15; y++) { for (x = 0; x <= 10; x++) { theX = x * 32; theY = y * 32; context.drawImage(tiles[5], theY, theX, 32, 32); } } } }; tiles.push(imageObj); } Naturally, when a player starts a game it loads the map they last left off. But for here, it an all-grass map. Right now, the maps use 2D arrays. Here's an example map. [[4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 1, 1, 1, 1], [1, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 13, 1, 1, 1, 1, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 13, 1, 13, 13, 1, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 13, 1, 13, 13, 1, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 13, 1, 13, 13, 1, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 13, 1, 1, 1, 1, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 13, 13, 13, 13, 1, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 13, 13, 11, 11, 11, 13, 13, 13, 13, 13, 13, 13, 1], [13, 13, 13, 1, 1, 1, 1, 1, 1, 1, 13, 13, 13, 13, 13, 1], [1, 1, 1, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 1, 1, 1]]; I get different maps using a simple if structure. Once the 2d array above is return, the corresponding number in each array will be painted according to Image() stored inside tile[]. Then drawImage() will occur and paint according to the x and y and times it by 32 to paint on the correct x-y coordinate. How multiple map switching occurs With my game, maps have five things to keep track of: currentID, leftID, rightID, upID, and bottomID. currentID: The current ID of the map you are on. leftID: What ID of currentID to load when you exit on the left of current map. rightID: What ID of currentID to load when you exit on the right of current map. downID: What ID of currentID to load when you exit on the bottom of current map. upID: What ID of currentID to load when you exit on the top of current map. Something to note: If either leftID, rightID, upID, or bottomID are NOT specific, that means they are a 0. That means they cannot leave that side of the map. It is merely an invisible blockade. So, once a person exits a side of the map, depending on where they exited... for example if they exited on the bottom, bottomID will the number of the map to load and thus be painted on the map. Here's a representational .GIF to help you better visualize: As you can see, sooner or later, with many maps I will be dealing with many IDs. And that can possibly get a little confusing and hectic. The obvious pros is that it load 176 tiles at a time, refresh a small 512x352 canvas, and handles one map at time. The con is that the MAP ids, when dealing with many maps, may get confusing at times. My question Is this an efficient way to store maps (given the usage of tiles), or is there a better way to handle maps? I was thinking along the lines of a giant map. The map-size is big and it's all one 2D array. The viewport, however, is still 512x352 pixels. Here's another .gif I made (for this question) to help visualize: Sorry if you cannot understand my English. Please ask anything you have trouble understanding. Hopefully, I made it clear. Thanks.

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• Developing Schema Compare for Oracle (Part 6): 9i Query Performance

  - by Simon Cooper

  All throughout the EAP and beta versions of Schema Compare for Oracle, our main request was support for Oracle 9i. After releasing version 1.0 with support for 10g and 11g, our next step was then to get version 1.1 of SCfO out with support for 9i. However, there were some significant problems that we had to overcome first. This post will concentrate on query execution time. When we first tested SCfO on a 9i server, after accounting for various changes to the data dictionary, we found that database registration was taking a long time. And I mean a looooooong time. The same database that on 10g or 11g would take a couple of minutes to register would be taking upwards of 30 mins on 9i. Obviously, this is not ideal, so a poke around the query execution plans was required. As an example, let's take the table population query - the one that reads ALL_TABLES and joins it with a few other dictionary views to get us back our list of tables. On 10g, this query takes 5.6 seconds. On 9i, it takes 89.47 seconds. The difference in execution plan is even more dramatic - here's the (edited) execution plan on 10g: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 108K| 939 || 1 | SORT ORDER BY | | 108K| 939 || 2 | NESTED LOOPS OUTER | | 108K| 938 ||* 3 | HASH JOIN RIGHT OUTER | | 103K| 762 || 4 | VIEW | ALL_EXTERNAL_LOCATIONS | 2058 | 3 ||* 20 | HASH JOIN RIGHT OUTER | | 73472 | 759 || 21 | VIEW | ALL_EXTERNAL_TABLES | 2097 | 3 ||* 34 | HASH JOIN RIGHT OUTER | | 39920 | 755 || 35 | VIEW | ALL_MVIEWS | 51 | 7 || 58 | NESTED LOOPS OUTER | | 39104 | 748 || 59 | VIEW | ALL_TABLES | 6704 | 668 || 89 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2025 | 5 || 106 | VIEW | ALL_PART_TABLES | 277 | 11 |------------------------------------------------------------------------------- And the same query on 9i: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 16P| 55G|| 1 | SORT ORDER BY | | 16P| 55G|| 2 | NESTED LOOPS OUTER | | 16P| 862M|| 3 | NESTED LOOPS OUTER | | 5251G| 992K|| 4 | NESTED LOOPS OUTER | | 4243M| 2578 || 5 | NESTED LOOPS OUTER | | 2669K| 1440 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 ||* 50 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2043 | ||* 66 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_TABLES | 1777K| ||* 80 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_LOCATIONS | 1744K| ||* 96 | VIEW | ALL_PART_TABLES | 852K| |------------------------------------------------------------------------------- Have a look at the cost column. 10g's overall query cost is 939, and 9i is 55,000,000,000 (or more precisely, 55,496,472,769). It's also having to process far more data. What on earth could be causing this huge difference in query cost? After trawling through the '10g New Features' documentation, we found item 1.9.2.21. Before 10g, Oracle advised that you do not collect statistics on data dictionary objects. From 10g, it advised that you do collect statistics on the data dictionary; for our queries, Oracle therefore knows what sort of data is in the dictionary tables, and so can generate an efficient execution plan. On 9i, no statistics are present on the system tables, so Oracle has to use the Rule Based Optimizer, which turns most LEFT JOINs into nested loops. If we force 9i to use hash joins, like 10g, we get a much better plan: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 7587K| 3704 || 1 | SORT ORDER BY | | 7587K| 3704 ||* 2 | HASH JOIN OUTER | | 7587K| 822 ||* 3 | HASH JOIN OUTER | | 5262K| 616 ||* 4 | HASH JOIN OUTER | | 2980K| 465 ||* 5 | HASH JOIN OUTER | | 710K| 432 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 || 50 | VIEW | ALL_PART_TABLES | 852K| 104 || 78 | VIEW | ALL_TAB_COMMENTS | 2043 | 14 || 93 | VIEW | ALL_EXTERNAL_LOCATIONS | 1744K| 31 || 106 | VIEW | ALL_EXTERNAL_TABLES | 1777K| 28 |------------------------------------------------------------------------------- That's much more like it. This drops the execution time down to 24 seconds. Not as good as 10g, but still an improvement. There are still several problems with this, however. 10g introduced a new join method - a right outer hash join (used in the first execution plan). The 9i query optimizer doesn't have this option available, so forcing a hash join means it has to hash the ALL_TABLES table, and furthermore re-hash it for every hash join in the execution plan; this could be thousands and thousands of rows. And although forcing hash joins somewhat alleviates this problem on our test systems, there's no guarantee that this will improve the execution time on customers' systems; it may even increase the time it takes (say, if all their tables are partitioned, or they've got a lot of materialized views). Ideally, we would want a solution that provides a speedup whatever the input. To try and get some ideas, we asked some oracle performance specialists to see if they had any ideas or tips. Their recommendation was to add a hidden hook into the product that allowed users to specify their own query hints, or even rewrite the queries entirely. However, we would prefer not to take that approach; as well as a lot of new infrastructure & a rewrite of the population code, it would have meant that any users of 9i would have to spend some time optimizing it to get it working on their system before they could use the product. Another approach was needed. All our population queries have a very specific pattern - a base table provides most of the information we need (ALL_TABLES for tables, or ALL_TAB_COLS for columns) and we do a left join to extra subsidiary tables that fill in gaps (for instance, ALL_PART_TABLES for partition information). All the left joins use the same set of columns to join on (typically the object owner & name), so we could re-use the hash information for each join, rather than re-hashing the same columns for every join. To allow us to do this, along with various other performance improvements that could be done for the specific query pattern we were using, we read all the tables individually and do a hash join on the client. Fortunately, this 'pure' algorithmic problem is the kind that can be very well optimized for expected real-world situations; as well as storing row data we're not using in the hash key on disk, we use very specific memory-efficient data structures to store all the information we need. This allows us to achieve a database population time that is as fast as on 10g, and even (in some situations) slightly faster, and a memory overhead of roughly 150 bytes per row of data in the result set (for schemas with 10,000 tables in that means an extra 1.4MB memory being used during population). Next: fun with the 9i dictionary views.

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• Understanding the 'High Performance' meaning in Extreme Transaction Processing

  - by kyap

  Despite my previous blogs entries on SOA/BPM and Identity Management, the domain where I'm the most passionated is definitely the Extreme Transaction Processing, commonly called XTP.I came across XTP back to 2007 while I was still FMW Product Manager in EMEA. At that time Oracle acquired a company called Tangosol, which owned an unique product called Coherence that we renamed to Oracle Coherence. Beside this innovative renaming of the product, to be honest, I didn't know much about it, except being a "distributed in-memory cache for Extreme Transaction Processing"... not very helpful still.In general when people doesn't fully understand a technology or a concept, they tend to find some shortcuts, either correct or not, to justify their lack-of understanding... and of course I was part of this category of individuals. And the shortcut was "Oracle Coherence Cache helps to improve Performance". Excellent marketing slogan... but not very meaningful still. By chance I was able to get away quickly from that group in July 2007* at Thames Valley Park (UK), after I attended one of the most interesting workshops, in my 10 years career in Oracle, delivered by Brian Oliver. The biggest mistake I made was to assume that performance improvement with Coherence was related to the response time. Which can be considered as legitimus at that time, because after-all caches help to reduce latency on cached data access, hence reduce the response-time. But like all caches, you need to define caching and expiration policies, thinking about the cache-missed strategy, and most of the time you have to re-write partially your application in order to work with the cache. At a result, the expected benefit vanishes... so, not very useful then?The key mistake I made was my perception or obsession on how performance improvement should be driven, but I strongly believe this is still a common problem to most of the developers. In fact we all know the that the performance of a system is generally presented by the Capacity (or Throughput), with the 2 important dimensions Speed (response-time) and Volume (load) :Capacity (TPS) = Volume (T) / Speed (S)To increase the Capacity, we can either reduce the Speed(in terms of response-time), or to increase the Volume. However we tend to only focus on reducing the Speed dimension, perhaps it is more concrete and tangible to measure, and nicer to present to our management because there's a direct impact onto the end-users experience. On the other hand, we assume the Volume can be addressed by the underlying hardware or software stack, so if we need more capacity (scale out), we just add more hardware or software. Unfortunately, the reality proves that IT is never as ideal as we assume...The challenge with Speed improvement approach is that it is generally difficult and costly to make things already fast... faster. And by adding Coherence will not necessarily help either. Even though we manage to do so, the Capacity can not increase forever because... the Speed can be influenced by the Volume. For all system, we always have a performance illustration as follow: In all traditional system, the increase of Volume (Transaction) will also increase the Speed (Response-Time) as some point. The reason is simple: most of the time the Application logics were not designed to scale. As an example, if you have a while-loop in your application, it is natural to conceive that parsing 200 entries will require double execution-time compared to 100 entries. If you need to "Speed-up" the execution, you can only upgrade your hardware (scale-up) with faster CPU and/or network to reduce network latency. It is technically limited and economically inefficient. And this is exactly where XTP and Coherence kick in. The primary objective of XTP is about designing applications which can scale-out for increasing the Volume, by applying coding techniques to keep the execution-time as constant as possible, independently of the number of runtime data being manipulated. It is actually not just about having an application running as fast as possible, but about having a much more predictable system, with constant response-time and linearly scale, so we can easily increase throughput by adding more hardwares in parallel. It is in general combined with the Low Latency Programming model, where we tried to optimize the network usage as much as possible, either from the programmatic angle (less network-hoops to complete a task), and/or from a hardware angle (faster network equipments). In this picture, Oracle Coherence can be considered as software-level XTP enabler, via the Distributed-Cache because it can guarantee: - Constant Data Objects access time, independently from the number of Objects and the Coherence Cluster size - Data Objects Distribution by Affinity for in-memory data grouping - In-place Data Processing for parallel executionTo summarize, Oracle Coherence is indeed useful to improve your application performance, just not in the way we commonly think. It's not about the Speed itself, but about the overall Capacity with Extreme Load while keeping consistant Speed. In the future I will keep adding new blog entries around this topic, with some sample codes experiences sharing that I capture in the last few years. In the meanwhile if you want to know more how Oracle Coherence, I strongly suggest you to start with checking how our worldwide customers are using Oracle Coherence first, then you can start playing with the product through our tutorial.Have Fun !

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• Page allocation failures on iSCSI storage

  - by Dave

  We have a CentOS 6.3 iscsi server (16GB RAM) running on Infiniband bus (ipoib). When the load is high I can see multiple errors: Sep 3 23:22:20 stor4 kernel: tgtd: page allocation failure. order:2, mode:0x20 Sep 3 23:22:20 stor4 kernel: Pid: 3637, comm: tgtd Not tainted 2.6.32 #1 Sep 3 23:22:20 stor4 kernel: Call Trace: Sep 3 23:22:20 stor4 kernel: [] ? __alloc_pages_nodemask+0x77f/0x940 Sep 3 23:22:20 stor4 kernel: [] ? kmem_getpages+0x62/0x170 Sep 3 23:22:20 stor4 kernel: [] ? fallback_alloc+0x1ba/0x270 Sep 3 23:22:20 stor4 kernel: [] ? cache_grow+0x2cf/0x320 Sep 3 23:22:20 stor4 kernel: [] ? ____cache_alloc_node+0x99/0x160 Sep 3 23:22:20 stor4 kernel: [] ? pskb_expand_head+0x64/0x270 Sep 3 23:22:20 stor4 kernel: [] ? __kmalloc+0x189/0x220 Sep 3 23:22:20 stor4 kernel: [] ? pskb_expand_head+0x64/0x270 Sep 3 23:22:20 stor4 kernel: [] ? __pskb_pull_tail+0x2aa/0x360 Sep 3 23:22:20 stor4 kernel: [] ? tcp_init_tso_segs+0x37/0x50 Sep 3 23:22:20 stor4 kernel: [] ? dev_queue_xmit+0x4bb/0x6f0 Sep 3 23:22:20 stor4 kernel: [] ? neigh_connected_output+0xbd/0x100 Sep 3 23:22:20 stor4 kernel: [] ? ip_finish_output+0x237/0x310 Sep 3 23:22:20 stor4 kernel: [] ? ip_output+0xb8/0xc0 Sep 3 23:22:20 stor4 kernel: [] ? __ip_local_out+0x9f/0xb0 Sep 3 23:22:20 stor4 kernel: [] ? ip_local_out+0x25/0x30 Sep 3 23:22:20 stor4 kernel: [] ? ip_queue_xmit+0x190/0x420 Sep 3 23:22:20 stor4 kernel: [] ? sock_aio_write+0x167/0x180 Sep 3 23:22:20 stor4 kernel: [] ? tcp_transmit_skb+0x3fe/0x7b0 Sep 3 23:22:20 stor4 kernel: [] ? tcp_write_xmit+0x1fb/0xa20 Sep 3 23:22:20 stor4 kernel: [] ? __tcp_push_pending_frames+0x30/0xe0 Sep 3 23:22:20 stor4 kernel: [] ? tcp_push_pending_frames+0x33/0x40 Sep 3 23:22:20 stor4 kernel: [] ? do_tcp_setsockopt+0x3d6/0x480 Sep 3 23:22:20 stor4 kernel: [] ? tcp_setsockopt+0x2a/0x30 Sep 3 23:22:20 stor4 kernel: [] ? sock_common_setsockopt+0x14/0x20 Sep 3 23:22:20 stor4 kernel: [] ? sys_setsockopt+0x7f/0xe0 Sep 3 23:22:20 stor4 kernel: [] ? system_call_fastpath+0x16/0x1b Sep 3 23:22:20 stor4 kernel: Mem-Info: Sep 3 23:22:20 stor4 kernel: Node 0 DMA per-cpu: Sep 3 23:22:20 stor4 kernel: CPU 0: hi: 0, btch: 1 usd: 0 Sep 3 23:22:20 stor4 kernel: CPU 1: hi: 0, btch: 1 usd: 0 Sep 3 23:22:20 stor4 kernel: CPU 2: hi: 0, btch: 1 usd: 0 Sep 3 23:22:20 stor4 kernel: CPU 3: hi: 0, btch: 1 usd: 0 Sep 3 23:22:20 stor4 kernel: Node 0 DMA32 per-cpu: Sep 3 23:22:20 stor4 kernel: CPU 0: hi: 186, btch: 31 usd: 183 Sep 3 23:22:20 stor4 kernel: CPU 1: hi: 186, btch: 31 usd: 23 Sep 3 23:22:20 stor4 kernel: CPU 2: hi: 186, btch: 31 usd: 183 Sep 3 23:22:20 stor4 kernel: CPU 3: hi: 186, btch: 31 usd: 181 Sep 3 23:22:20 stor4 kernel: Node 0 Normal per-cpu: Sep 3 23:22:20 stor4 kernel: CPU 0: hi: 186, btch: 31 usd: 171 Sep 3 23:22:20 stor4 kernel: CPU 1: hi: 186, btch: 31 usd: 29 Sep 3 23:22:20 stor4 kernel: CPU 2: hi: 186, btch: 31 usd: 32 Sep 3 23:22:20 stor4 kernel: CPU 3: hi: 186, btch: 31 usd: 32 Sep 3 23:22:20 stor4 kernel: active_anon:1875 inactive_anon:2473 isolated_anon:0 Sep 3 23:22:20 stor4 kernel: active_file:1243637 inactive_file:2505055 isolated_file:0 Sep 3 23:22:20 stor4 kernel: unevictable:0 dirty:268338 writeback:0 unstable:0 Sep 3 23:22:20 stor4 kernel: free:86050 slab_reclaimable:132377 slab_unreclaimable:23744 Sep 3 23:22:20 stor4 kernel: mapped:1293 shmem:222 pagetables:720 bounce:0 Sep 3 23:22:20 stor4 kernel: Node 0 DMA free:15732kB min:124kB low:152kB high:184kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15332kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes Sep 3 23:22:20 stor4 kernel: lowmem_reserve[]: 0 2172 16060 16060 Sep 3 23:22:20 stor4 kernel: Node 0 DMA32 free:107544kB min:18268kB low:22832kB high:27400kB active_anon:468kB inactive_anon:2364kB active_file:566208kB inactive_file:976112kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:2224900kB mlocked:0kB dirty:96816kB writeback:0kB mapped:908kB shmem:12kB slab_reclaimable:176940kB slab_unreclaimable:968kB kernel_stack:64kB pagetables:192kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no Sep 3 23:22:20 stor4 kernel: lowmem_reserve[]: 0 0 13887 13887 Sep 3 23:22:20 stor4 kernel: Node 0 Normal free:220924kB min:116772kB low:145964kB high:175156kB active_anon:7032kB inactive_anon:7528kB active_file:4408340kB inactive_file:9044108kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:14220800kB mlocked:0kB dirty:976536kB writeback:0kB mapped:4264kB shmem:876kB slab_reclaimable:352568kB slab_unreclaimable:94008kB kernel_stack:2048kB pagetables:2688kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no Sep 3 23:22:20 stor4 kernel: lowmem_reserve[]: 0 0 0 0 Sep 3 23:22:20 stor4 kernel: Node 0 DMA: 1*4kB 0*8kB 1*16kB 1*32kB 1*64kB 0*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 3*4096kB = 15732kB Sep 3 23:22:20 stor4 kernel: Node 0 DMA32: 16305*4kB 4381*8kB 353*16kB 8*32kB 1*64kB 1*128kB 0*256kB 1*512kB 1*1024kB 0*2048kB 0*4096kB = 107900kB Sep 3 23:22:20 stor4 kernel: Node 0 Normal: 14548*4kB 14808*8kB 2420*16kB 31*32kB 5*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 1*4096kB = 220784kB Sep 3 23:22:20 stor4 kernel: 3748822 total pagecache pages Sep 3 23:22:20 stor4 kernel: 0 pages in swap cache Sep 3 23:22:20 stor4 kernel: Swap cache stats: add 0, delete 0, find 0/0 Sep 3 23:22:20 stor4 kernel: Free swap = 975864kB Sep 3 23:22:20 stor4 kernel: Total swap = 975864kB Sep 3 23:22:20 stor4 kernel: 4194303 pages RAM Sep 3 23:22:20 stor4 kernel: 126915 pages reserved Sep 3 23:22:20 stor4 kernel: 3753534 pages shared Sep 3 23:22:20 stor4 kernel: 213500 pages non-shared TCP stack and VM config: net.core.rmem_max = 83886080 net.core.wmem_max = 83886080 net.core.rmem_default = 65536 net.core.wmem_default = 65536 net.ipv4.tcp_rmem = 40960 1048560 4194304 net.ipv4.tcp_wmem = 40960 196608 4194304 net.ipv4.tcp_mem = 16388608 16388608 16388608 vm.min_free_kbytes=135168 Additional tweaks: /sbin/blockdev --setra 16384 /dev/sdb echo 2048 /sys/block/sdb/queue/nr_requests Where might the problem be? Thank you.

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• University teaches DOS-style C++, how to deal with it

  - by gaidal

  Half a year ago I had a look at available programming educations. I chose this one because unlike most of the choices: The majority of the courses seemed to be about something concrete and useful; the languages used are C++ and Java which are platform-independent; later courses include developing for mobile devices and a course on Android development, which seemed modern and relevant. Now after two introductory courses we're just starting with C++, and my programming professor seems a bit weird. He's tested us on things like "why should you use constants" and "why are globals bad" in a kind of mechanical way, without much context, before teaching actual programming. His handouts use system("pause"), system("cls"), and getch() from some conio.h that seems ancient according to what I've read. I just did a task that was about printing the "ASCII letters from 32 to 255" (huh?), with an example picture showing a table with Windows' Extended ASCII - of course I got other results for 128-255 on my Arch Linux that uses Unicode, and this isn't mentioned at all. I don't know, it just doesn't seem right... As if he is teaching programming because he has to, perhaps? Should I bring such things up? Hmm. I was looking forward to learning from someone who really knows stuff, and in an academic, rigorous way, like SICP or something. Aren't professors in programming supposed to be like that? I studied math for a while and every teacher and assistant there were really precise about what they said, but this is my second programming teacher that is sort of disappointing. Oh well. Now, question: Is this what to expect from universities or Not OK, and how do I deal with it? I have never touched the language C++ (or C) until now, and am not the right person to jump up and say "This is So Wrong!", so if I google something and find 10 people who say "xxx is blasphemy", how do I skillfully communicate this? I do think it would be better for those classmates who are total beginners not to learn bad habits (such as these vibes of total ignorance of other platforms!) during the upcoming courses, but don't want to disrespect the teacher. I don't know if it's reasonable or just cocky to bring up things like "what about other platforms?" or "but what about this article or stackoverflow answer that I read that said..." for every assignment? Or, if he keeps ignoring non-Windows-programming, should I give up and focus on my own projects or somehow argue that this really isn't OK nowadays? Are there any programming teachers out there, what do you think? By the way these are web-based courses, all interaction between teachers and students takes place in a forum. EDIT: A few answers seem to be making some incorrect assumptions, so maybe I should add a few things. I have been doing programming for fun on and off for 10 years, am pretty comfortable in 3 languages and read programming blogs et c regularly. Also, I feel kind of done being a student, having a degree in another field. I just need another, relevant diploma to work as a programmer, so I'm going back for that. Studying computer science for 5 years is not for me anymore, even though I enjoy learning and solving problems in my free time. Second, let me highlight that I don't expect it to be like the industry at all, quite the contrary. I expect it to be academic, dry and unnecessarily correct. No, it's not just math. Every professor I have had in math, or Japanese (major) or Chinese (minor) have been very very academic, discussing subtle points for hours with passion. But the courses I'm taking now and a previous one in programming don't seem serious. They neither resemble industry NOR academia. That is the problem. And it's not because I can't learn programming anyway. Third, I don't necessarily want to learn C++ or Android development, and I know I could teach myself those and anything else if I wanted to. But I am going back to school anyway, and those platform-independent languages and mobile stuff made me think that maybe they're serious about teaching something relevant here. Seems like I got this wrong, but we'll see.

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• Synergy - easy share of keyboard and mouse between multiple computers

  Did you ever have the urge to share one set of keyboard and mouse between multiple machines? If so, please read on... Using multiple machines Honestly, as a software craftsman it is my daily business to run multiple machines - either physical or virtual - to be able to solve my customers' requirements. Recent hardware equipment allows this very easily. For laptops it's a no-brainer to attach a second or even a third screen in order to extend your native display. This works quite handy and in my case I used to attached two additional screens - one via HD15 connector, the other via HDMI. But... as it's a laptop and therefore a mobile unit there are slight restrictions. Detaching and re-attaching all cables when changing locations is one of them but hardware limitations, too. After all, it's a laptop and not a workstation. I guess, that anyone working in IT (or ICT) has more than one machine at their workplace or their home office and at least I find it quite annoying to have multiple sets of keyboard and mouse conquering my remaining space on my desk. Despite the ugly looks of all those cables and whatsoever 'chaos of distraction' I prefer a more clean solution and working environment. This allows me to actually focus on my work and tasks to do rather than to worry about choosing the right combination of keyboard/mouse. My current workplace is a patch work of various pieces of hardware (approx. 2-3 years): DIY desktop on Ubuntu 12.04 64-bit, Core2 Duo (E7400, 2.8GHz), 4GB RAM, 2x 250GB HDD, nVidia GPU 512MB Dell Inspiron 1525 on Windows 8 64-bit, 4GB RAM, 200GB HDD HP Compaq 6720s on Windows Vista 32-bit, Core2 Duo (T5670, 1.8GHz), 2GB RAM, 160GB HDD Mac mini on Mac OS X 10.7, Core i5 (2.3 GHz), 2GB RAM, 500GB HDD I know... Not the latest and greatest but a decent combination to work with. New system(s) is/are already on the shopping list but I live in the 'wrong' country to buy computer hardware. So, the next trip abroad will provide me with some new stuff. Using multiple operating systems The list of hardware above already names different operating systems, and actually I have only one preference: Linux. But still my job as a software craftsman for Visual FoxPro and .NET development requires other OSes, too. Not a big deal, it's just like this. Additionally to those physical machines, there are a bunch of virtual machines around. Most of them running either Windows XP or Windows 7. Since years I have the practice that each development for one customer is isolated into its own virtual machine and environment. This keeps it clean and version-safe. But as you can easily imagine with that setup there are a couple of constraints referring to keyboard and mouse. Usually, those systems require their own pieces of hardware attached. As stated, I don't like clutter on my desk's surface, so a cross-platform solution has to come in here. In the past, I tried it with various applications, hardware or network protocols like X11, RDP, NX, TeamViewer, RAdmin, KVM switch, etc. but the problem in this case is that they either allow you to remotely connect to the other system or exclusively 'bind' your peripherals to the active system. Not optimal after all. Synergy to the rescue Quote from their website: "Synergy lets you easily share your mouse and keyboard between multiple computers on your desk, and it's Free and Open Source. Just move your mouse off the edge of one computer's screen on to another. You can even share all of your clipboards. All you need is a network connection. Synergy is cross-platform (works on Windows, Mac OS X and Linux)." Yep, that's it! All I need for my setup here... Actually, I couldn't believe it myself that I didn't stumble over synergy earlier but 'Get over it' and there we go. And despite the fact that it is Open Source, no, it's also for free. Donations for the developers are very welcome and recently they introduced Synergy Premium. A possibility to buy so-called premium votes that can be used to put more weight / importance on specific issues or bugs that you would like the developers to look into. Installation and configuration Simply download the installation packages for your systems of choice, run the installer and enter some minor information about your network setup. I chose my desktop machine for the role of the Synergy server and configured my screen setup as follows: The screen setup allows you currently to build or connect up to 15 machines. The number of screens can be higher as those machine might have multiple screens physically attached. Synergy takes this into the overall calculations and simply works as expected. I tried it for fun with a second monitor each connected to both laptops to have a total number of 6 active screens. No flaws after all - stunning! All the other machines are configured as clients like so: Side note: The screenshot was taken on Windows 8 and pasted via clipboard into Gimp running on Ubuntu. Resume Synergy is now definitely in my box of tools for my daily work, and amongst the first pieces of software I install after the operating system. It just simplifies my life and cleans my desk. Never again without Synergy!Now, only waiting for an Android version to integrate my Galaxy Tab 10.1, too. ;-) Please, check out that superb product and enjoy sharing one keyboard, one mouse and one clipboard between your various machines and operating systems.

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• Server HTTP Load times slow?

  - by cdog5000

  Hello, My server @ codemeh.com (HTTP Server) seems to be randomly loading slowly, I cannot tell if it just my forums (http://www.codemeh.com/forums/) that are loading slowly or if the WHOLE site is just loading slowly since my forums are the largest thing on the site right now. load average: 0.02, 0.17, 0.20 That is super low to my knowledge. I have tried Google Page Analytic plug-in for FireFox to solve the problem but nothing comes up that is VERY bad. If someone could investigate this for me since I am very new at apache and server configurations. Thanks! (top): PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 7493 www-data 15 0 98.2m 16m 9092 S 3 0.8 0:27.24 apache2 26429 www-data 15 0 98.2m 15m 7392 S 3 0.7 0:03.45 apache2 26477 www-data 17 0 98.2m 15m 7396 S 3 0.7 0:03.16 apache2 1 root 15 0 2468 1384 1156 S 0 0.1 0:00.49 init 1367 root 25 0 2564 816 660 S 0 0.0 0:00.00 xinetd 1526 root 15 0 29576 5420 1976 S 0 0.3 1:02.69 fail2ban-server 3703 root 15 0 13512 9312 1696 S 0 0.4 0:11.59 miniserv.pl 3915 postfix 15 0 6056 1652 1320 S 0 0.1 0:00.00 pickup 4010 root 15 0 4548 1296 972 S 0 0.1 0:37.36 ntpd 7448 root 15 0 98528 26m 20m S 0 1.3 0:00.27 apache2 7454 www-data 18 0 33580 2616 368 S 0 0.1 0:00.04 apache2 7528 www-data 18 0 108m 24m 15m S 0 1.2 0:27.60 apache2 7974 root 16 0 8700 2728 2164 S 0 0.1 0:00.08 sshd 8123 cdog5000 15 0 8832 1596 896 S 0 0.1 0:00.00 sshd 8126 cdog5000 18 0 4484 1716 1384 S 0 0.1 0:00.00 bash 8141 cdog5000 15 0 2344 980 796 R 0 0.0 0:00.11 top 13461 root 15 0 8700 2728 2164 S 0 0.1 0:00.07 sshd 13567 cdog5000 18 0 8832 1492 896 S 0 0.1 0:00.33 sshd 13569 cdog5000 18 0 4484 1728 1388 S 0 0.1 0:00.09 bash 17983 root 15 0 4392 1268 988 S 0 0.1 0:00.00 su 17987 root 15 0 4516 1752 1380 S 0 0.1 0:00.09 bash 18081 www-data 15 0 98.2m 14m 6588 S 0 0.7 0:04.91 apache2 20000 www-data 15 0 98.3m 15m 8040 S 0 0.8 0:02.45 apache2 20019 www-data 15 0 98.2m 14m 6808 S 0 0.7 0:04.97 apache2 30343 root 15 0 3964 1012 764 S 0 0.0 0:00.03 vsftpd 30382 root 15 0 2304 908 716 S 0 0.0 0:00.62 cron 30401 mysql 17 0 141m 17m 5416 S 0 0.9 1:02.20 mysqld 30424 root 15 0 5472 912 504 S 0 0.0 0:00.04 sshd 30473 syslog 15 0 1916 676 536 S 0 0.0 0:01.02 syslogd 30611 amavis 15 0 33872 25m 2292 S 0 1.2 0:03.11 amavisd-new 31890 amavis 18 0 34888 24m 1792 S 0 1.2 0:00.00 amavisd-new 31891 amavis 18 0 34888 24m 1784 S 0 1.2 0:00.00 amavisd-new 32397 clamav 18 0 104m 84m 1272 S 0 4.1 1:06.46 clamd 32563 clamav 15 0 12832 5716 4440 S 0 0.3 0:01.29 freshclam 32573 root 23 0 1892 456 372 S 0 0.0 0:00.00 courierlogger 32575 root 18 0 2096 684 544 S 0 0.0 0:00.01 authdaemond 32583 root 23 0 1892 360 284 S 0 0.0 0:00.00 courierlogger 32584 root 24 0 2000 612 516 S 0 0.0 0:00.00 couriertcpd 32598 root 23 0 1892 360 284 S 0 0.0 0:00.00 courierlogger 32599 root 25 0 2000 612 516 S 0 0.0 0:00.00 couriertcpd 32604 root 18 0 1892 460 372 S 0 0.0 0:00.00 courierlogger 32605 root 18 0 2000 624 532 S 0 0.0 0:00.00 couriertcpd 32607 root 18 0 2308 404 256 S 0 0.0 0:00.02 authdaemond 32608 root 18 0 2096 260 116 S 0 0.0 0:00.03 authdaemond 32609 root 15 0 2308 404 256 S 0 0.0 0:00.03 authdaemond 32610 root 18 0 2096 260 116 S 0 0.0 0:00.02 authdaemond 32612 root 18 0 2308 404 256 S 0 0.0 0:00.02 authdaemond 32621 root 24 0 1892 364 284 S 0 0.0 0:00.00 courierlogger 32622 root 25 0 2000 608 516 S 0 0.0 0:00.00 couriertcpd 32633 root 15 0 105m 936 716 S 0 0.0 0:02.26 nscd 32719 root 16 0 6252 1680 1344 S 0 0.1 0:01.24 master 32738 postfix 15 0 6188 1776 1400 S 0 0.1 0:00.44 qmgr 32758 postfix 15 0 6492 2564 1788 S 0 0.1 0:00.14 tlsmgr (/etc/apache2/sites-available/default): NameVirtualHost * <VirtualHost *> ServerAdmin webmaster@localhost DocumentRoot /var/www/web1/web/ <Directory /var/www/web1/web/> Options Indexes MultiViews AllowOverride None Order allow,deny allow from all </Directory> </VirtualHost> I have fail2ban server and I dont have any firewall at this point and time that I know of. SMF is 2.0 RC4 and apache version is 2.2.14. I run a MySQL server on another box in the same DC (Persistent Connection). I installed eAccelerator today and it didnt help.

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• How to Hashtag (Without Being #Annoying)

  - by Mike Stiles

  The right tool in the wrong hands can be a dangerous thing. Giving a chimpanzee a chain saw would not be a pretty picture. And putting Twitter hashtags in the hands of social marketers who were never really sure how to use them can be equally unattractive. Boiled down, hashtags are for search and organization of tweets. A notch up from that, they can also be used as part of a marketing strategy. In terms of search, if you’re in the organic apple business, you want anyone who searches “organic” on Twitter to see your posts about your apples. It’s keyword tactics not unlike web site keyword search tactics. So get a clear idea of what keywords are relevant for your tweet. It’s reasonable to include #organic in your tweet. Is it fatal if you don’t hashtag the word? It depends on the person searching. If they search “organic,” your tweet’s going to come up even if you didn’t put the hashtag in front of it. If the searcher enters “#organic,” your tweet needs the hashtag. Err on the side of caution and hashtag it so it comes up no matter how the searcher enters it. You’ll also want to hashtag it for the second big reason people hashtag, organization. You can follow a hashtag. So can the rest of the Twitterverse. If you’re that into organic munchies, you can set up a stream populated only with tweets hashtagged #organic. If you’ve established a hashtag for your brand, like #nobugsprayapples, you (and everyone else) can watch what people are tweeting about your company. So what kind of hashtags should you include? They should be directly related to the core message of your tweet. Ancillary or very loosely-related hashtags = annoying. Hashtagging your brand makes sense. Hashtagging your core area of interest makes sense. Creating a specific event or campaign hashtag you want others to include and spread makes sense (the burden is on you to promote it and get it going). Hashtagging nearly every word in the tweet is highly annoying. Far and away, the majority of hashtagged words in such tweets have no relevance, are not terms that would be searched, and are not terms needed for categorization. It looks desperate and spammy. Two is fine. One is better. And it is possible to tweet with --gasp-- no hashtags! Make your hashtags as short as you can. In fact, if your brand’s name really is #nobugsprayapples, you’re burning up valuable, limited characters and risking the inability of others to retweet with added comments. Also try to narrow your topic hashtag down. You’ll find a lot of relevant users with #organic, but a lot of totally uninterested users with #food. Just as you can join online forums and gain credibility and a reputation by contributing regularly to that forum, you can follow hashtagged topics and gain the same kind of credibility in your area of expertise. Don’t just parachute in for the occasional marketing message. And if you’re constantly retweeting one particular person, stop it. It’s kissing up and it’s obvious. Which brings us to the king of hashtag annoyances, “hashjacking.” This is when you see what terms are hot and include them in your marketing tweet as a hashtag, even though it’s unrelated to your content. Justify it all you want, but #justinbieber has nothing to do with your organic apples. Equally annoying, piggybacking on a popular event’s hashtag to tweet something not connected to the event. You’re only fostering ill will and mistrust toward your account from the people you’ve tricked into seeing your tweet. Lastly, don’t @ mention people just to make sure they see your tweet. If the tweet’s not for them or about them, it’s spammy. What I haven’t covered is use of the hashtag for comedy’s sake. You’ll see this a lot and is a matter of personal taste. No one will search these hashtagged terms or need to categorize then, they’re just there for self-expression and laughs. Twitter is, after all, supposed to be fun.  What are some of your biggest Twitter pet peeves? #blogsovernow

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• e2fsck extremly slow, although enough memory exists

  - by kaefert

  I've got this external USB-Disk: kaefert@blechmobil:~$ lsusb -s 2:3 Bus 002 Device 003: ID 0bc2:3320 Seagate RSS LLC As can be seen in this dmesg output, there are some problems that prevents that disk from beeing mounted: kaefert@blechmobil:~$ dmesg | grep sdb [ 114.474342] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.475089] sd 5:0:0:0: [sdb] Write Protect is off [ 114.475092] sd 5:0:0:0: [sdb] Mode Sense: 43 00 00 00 [ 114.475959] sd 5:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 114.477093] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.501649] sdb: sdb1 [ 114.502717] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.504354] sd 5:0:0:0: [sdb] Attached SCSI disk [ 116.804408] EXT4-fs (sdb1): ext4_check_descriptors: Checksum for group 3976 failed (47397!=61519) [ 116.804413] EXT4-fs (sdb1): group descriptors corrupted! So I went and fired up my favorite partition manager - gparted, and told it to verify and repair the partition sdb1. This made gparted call e2fsck (version 1.42.4 (12-Jun-2012)) e2fsck -f -y -v /dev/sdb1 Although gparted called e2fsck with the "-v" option, sadly it doesn't show me the output of my e2fsck process (bugreport https://bugzilla.gnome.org/show_bug.cgi?id=467925 ) I started this whole thing on Sunday (2012-11-04_2200) evening, so about 48 hours ago, this is what htop says about it now (2012-11-06-1900): PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command 3704 root 39 19 1560M 1166M 768 R 98.0 19.5 42h56:43 e2fsck -f -y -v /dev/sdb1 Now I found a few posts on the internet that discuss e2fsck running slow, for example: http://gparted-forum.surf4.info/viewtopic.php?id=13613 where they write that its a good idea to see if the disk is just that slow because maybe its damaged, and I think these outputs tell me that this is not the case in my case: kaefert@blechmobil:~$ sudo hdparm -tT /dev/sdb /dev/sdb: Timing cached reads: 3562 MB in 2.00 seconds = 1783.29 MB/sec Timing buffered disk reads: 82 MB in 3.01 seconds = 27.26 MB/sec kaefert@blechmobil:~$ sudo hdparm /dev/sdb /dev/sdb: multcount = 0 (off) readonly = 0 (off) readahead = 256 (on) geometry = 364801/255/63, sectors = 5860533160, start = 0 However, although I can read quickly from that disk, this disk speed doesn't seem to be used by e2fsck, considering tools like gkrellm or iotop or this: kaefert@blechmobil:~$ iostat -x Linux 3.2.0-2-amd64 (blechmobil) 2012-11-06 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 14,24 47,81 14,63 0,95 0,00 22,37 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0,59 8,29 2,42 5,14 43,17 160,17 53,75 0,30 39,80 8,72 54,42 3,95 2,99 sdb 137,54 5,48 9,23 0,20 587,07 22,73 129,35 0,07 7,70 7,51 16,18 2,17 2,04 Now I researched a little bit on how to find out what e2fsck is doing with all that processor time, and I found the tool strace, which gives me this: kaefert@blechmobil:~$ sudo strace -p3704 lseek(4, 41026998272, SEEK_SET) = 41026998272 write(4, "\212\354K[_\361\3nl\212\245\352\255jR\303\354\312Yv\334p\253r\217\265\3567\325\257\3766"..., 4096) = 4096 lseek(4, 48404766720, SEEK_SET) = 48404766720 read(4, "\7t\260\366\346\337\304\210\33\267j\35\377'\31f\372\252\ffU\317.y\211\360\36\240c\30`\34"..., 4096) = 4096 lseek(4, 41027002368, SEEK_SET) = 41027002368 write(4, "\232]7Ws\321\352\t\1@[+5\263\334\276{\343zZx\352\21\316`1\271[\202\350R`"..., 4096) = 4096 lseek(4, 48404770816, SEEK_SET) = 48404770816 read(4, "\17\362r\230\327\25\346//\210H\v\311\3237\323K\304\306\361a\223\311\324\272?\213\tq \370\24"..., 4096) = 4096 lseek(4, 41027006464, SEEK_SET) = 41027006464 write(4, "\367yy>x\216?=\324Z\305\351\376&\25\244\210\271\22\306}\276\237\370(\214\205G\262\360\257#"..., 4096) = 4096 lseek(4, 48404774912, SEEK_SET) = 48404774912 read(4, "\365\25\0\21|T\0\21}3t_\272\373\222k\r\177\303\1\201\261\221$\261B\232\3142\21U\316"..., 4096) = 4096 ^CProcess 3704 detached around 16 of these lines every second, so 4 read and 4 write operations every second, which I don't consider to be a lot.. And finally, my question: Will this process ever finish? If those numbers from fseek (48404774912) represent bytes, that would be something like 45 gigabytes, with this beeing a 3 terrabyte disk, which would give me 134 days to go, if the speed stays constant, and he scans the disk like this completly and only once. Do you have some advice for me? I have most of the data on that disk elsewhere, but I've put a lot of hours into sorting and merging it to this disk, so I would prefer to getting this disk up and running again, without formatting it anew. I don't think that the hardware is damaged since the disk is only a few months and since I can't see any I/O errors in the dmesg output. UPDATE: I just looked at the strace output again (2012-11-06_2300), now it looks like this: lseek(4, 1419860611072, SEEK_SET) = 1419860611072 read(4, "3#\f\2447\335\0\22A\355\374\276j\204'\207|\217V|\23\245[\7VP\251\242\276\207\317:"..., 4096) = 4096 lseek(4, 43018145792, SEEK_SET) = 43018145792 write(4, "]\206\231\342Y\204-2I\362\242\344\6R\205\361\324\177\265\317C\334V\324\260\334\275t=\10F."..., 4096) = 4096 lseek(4, 1419860615168, SEEK_SET) = 1419860615168 read(4, "\262\305\314Y\367\37x\326\245\226\226\320N\333$s\34\204\311\222\7\315\236\336\300TK\337\264\236\211n"..., 4096) = 4096 lseek(4, 43018149888, SEEK_SET) = 43018149888 write(4, "\271\224m\311\224\25!I\376\16;\377\0\223H\25Yd\201Y\342\r\203\271\24eG<\202{\373V"..., 4096) = 4096 lseek(4, 1419860619264, SEEK_SET) = 1419860619264 read(4, ";d\360\177\n\346\253\210\222|\250\352T\335M\33\260\320\261\7g\222P\344H?t\240\20\2548\310"..., 4096) = 4096 lseek(4, 43018153984, SEEK_SET) = 43018153984 write(4, "\360\252j\317\310\251G\227\335{\214`\341\267\31Y\202\360\v\374\307oq\3063\217Z\223\313\36D\211"..., 4096) = 4096 So this number of the lseeks before the reads, like 1419860619264 are already a lot bigger, standing for 1.29 terabytes if the numbers are bytes, so it doesn't seem to be a linear progress on a big scale, maybe there are only some areas that need work, that have big gaps in between them. (times are in CET)

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• Windows 8/Surface Lunch Event Summary

  - by Tim Murphy

  Today was a big day for Microsoft with two separate launch event.  The first for Windows 8 and all of it’s hardware partners.  The second was specifically to introduce the Microsoft Windows 8 Surface tablet.  Below are some of the take-aways I got from the webcasts. Windows 8 Launch The three general area that Microsoft focused on were the release of the OS itself, the public unveiling of the Windows Store and the new devices available from its hardware partners. The release of the OS focused on the fact that it will be available at mid-night tonight for both new PCs and for upgrades.  I can’t say that this interested me that much since it was already known to most people.  I think what they did show well was how easy the OS really is to use. The Windows Store is also not a new feature to those of us who have been running the pre-release versions of Windows 8 or have owned Windows Phone 7 for the past 2 years.  What was interesting is that the Windows Store launches with more apps available than any other platforms store at their respective launch.  I think this says a lot about how Microsoft focuses on the ability of developers to create software and make it available.  The of course were sure to emphasize that the Windows Store has better monetary terms for developers than its competitors. The also showed off the fact that XBox Music streaming is available for to all Windows 8 user for free.  Couple this with the Bing suite of apps that give you news, weather, sports and finance right out of the box and I think most people will find the environment a joy to use. I think the hardware demo, while quick and furious, really show where Windows shine: CHOICE!  They made a statement that over 1000 devices have been certified for Windows 8.  They showed tablets, laptops, desktops, all-in-ones and convertibles.  Since these devices have industry standard connectors they give a much wider variety of accessories and devices that you can use with them. Steve Balmer then came on stage and tried to see how many times he could use the “magical”.  He focused on how the Windows 8 OS is designed to integrate with SkyDrive, Skype and Outlook.com.  He also enforced that they think Windows 8 is the best choice for the Enterprise when it comes to protecting data and integrating across devices including Windows Phone 8. With that we were left to wait for the second event of the day. Surface Launch The second event of the day started with kids with magnets.  Ok, they were adults, but who doesn’t like playing with magnets.  Steven Sinofsky detached and reattached the Surface keyboard repeatedly, clearly enjoying himself.  It turns out that there are 4 magnets in the cover, 2 for alignment and 2 as connectors. They then went to giving us the details on the display.  The 10.6” display is optically bonded to the case and is optimized to reduce glare.  I think this came through very well in the demonstrations. The properties of the case were also a great selling point.  The VaporMg allowed them to drop the device on stage, on purpose, and continue working.  Of course they had to bring out the skate boards made from Surface devices. “It just has to feel right” was the reason they gave for many of their design decisions from the weight and size of the device to the way the kickstand and camera work together.  While this gave you the feeling that the whole process was trial and error you could tell that a lot of science went into the specs.  This included making sure that the magnets were strong enough to hold the cover on and still have a 3 year old remove the cover without effort. I am glad that they also decided the a USB port would be part of the spec since it give so many options.  They made the point that this allows Surface to leverage over 420 million existing devices.  That works for me. The last feature that I really thought was important was the microSD port.  Begin stuck with the onboard memory has been an aggravation of mine with many of the devices in the market today. I think they did job of really getting the audience to understand why you want this platform and this particular device.  Using personal examples like creating a video of a birthday party and being in it or the fact that the device was being used to live blog the event and control the lights and presentation.  They showed very well that it was not only fun but very capable of getting real work done.  Handing out tablets to the crowd didn’t hurt either.  In the end I really wanted a Surface even though I really have no need for one on a daily basis.  Great job Microsoft! del.icio.us Tags: Windows 8,Win8,Windows 8 Luanch

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