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• Using all Ten IO slots on a 7420

  - by user12620172

  So I had the opportunity recently to actually use up all ten slots in a clustered 7420 system. This actually uses 20 slots, or 22 if you count the clusteron card. I thought it was interesting enough to share here. This is at one of my clients here in southern California. You can see the picture below. We have four SAS HBAs instead of the usual two. This is becuase we wanted to split up the back-end taffic for different workloads. We have a set of disk trays coming from two SAS cards for nothing but Exadata backups. Then, we have a different set of disk trays coming off of the other two SAS cards for non-Exadata workloads, such as regular user file storage. We have 2 Infiniband cards which allow us to do a full mesh directly into the back of the nearby, production Exadata, specifically for fast backups and restores over IB. You can see a 3rd IB card here, which is going to be connected to a non-production Exadata for slower backups and restores from it.The 10Gig card is for client connectivity, allowing other, non-Exadata Oracle databases to make use of the many snapshots and clones that can now be created using the RMAN copies from the original production database coming off the Exadata. This allows for a good number of test and development Oracle databases to use these clones without effecting performance of the Exadata at all.We also have a couple FC HBAs, both for NDMP backups to an Oracle/StorageTek tape library and also for FC clients to come in and use some storage on the 7420.  Now, if you are adding more cards to your 7420, be aware of which cards you can place in which slots. See the bottom graphic just below the photo.  Note that the slots are numbered 0-4 for the first 5 cards, then the "C" slots which is the dedicated Cluster card (called the Clustron), and then another 5 slots numbered 5-9. Some rules for the slots: Slots 1 & 8 are automatically populated with the two default SAS cards. The only other slots you can add SAS cards to are 2 & 7. Slots 0 and 9 can only hold FC cards. Nothing else. So if you have four SAS cards, you are now down to only four more slots for your 10Gig and IB cards. Be sure not to waste one of these slots on a FC card, which can go into 0 or 9, instead.  If at all possible, slots should be populated in this order: 9, 0, 7, 2, 6, 3, 5, 4

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• WCF Routing Service Filter Generator

  - by Michael Stephenson

  Recently I've been working with the WCF routing service and in our case we were simply routing based on the SOAP Action. This is a pretty good approach for a standard redirection of the message when all messages matching a SOAP Action will go to the same endpoint. Using the SOAP Action also lets you be specific about which methods you expose via the router. One of the things which was a pain was the number of routing rules I needed to create because we were routing for a lot of different methods. I could have explored the option of using a regular expression to match the message to its routing but I wanted to be very specific about what's routed and not risk exposing methods I shouldn't via the router. I decided to put together a little spreadsheet so that I can generate part of the configuration I would need to put in the configuration file rather than have to type this by hand. To show how this works download the spreadsheet from the following url: https://s3.amazonaws.com/CSCBlogSamples/WCF+Routing+Generator.xlsx In the spreadsheet you will see that the squares in green are the ones which you need to amend. In the below picture you can see that you specify a prefix and suffix for the filter name. The core namespace from the web service your generating routing rules for and the WCF endpoint name which you want to route to. In column A you will see the green cells where you add the list of method names which you want to include routing rules for. The spreadsheet will workout what the full SOAP Action would be then the name you will use for that filter in your WCF Routing filters. In column D the spreadsheet will have generated the XML snippet which you can add to the routing filters section in your configuration file. In column E the spreadsheet will have created the XML snippet which you can add to the routing table to send messages matching each filter to the appropriate WCF client endpoint to forward the message to the required destination. Hopefully you can see that with this spreadsheet it would be very easy to produce accurate XML for the WCF Routing configuration if you had a large number of routing rules. If you had additional methods in other services you can simply copy the worksheet and add multiple copies to the Excel workbook. One worksheet per service would work well.

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• Testing and Validation – You Really Do Have The Time

  - by BuckWoody

  One of the great advantages in my role as a Technical Specialist here at Microsoft is that I get to work with so many great clients. I get to see their environments and how they use them, and the way they work with SQL Server. I’ve been a data professional myself for many years. Over that time I’ve worked with many database platforms, lots of client applications, and written a lot of code in many industries. For a while I was also a consultant, so I got to see how other shops did things as well. But because I now focus on a “set” base of clients (over 500 professionals in over 150 companies) I get to see them over a longer period of time. Many of them help me understand how they use the product in their projects, and I even attend some DBA regular meetings. I see the way the product succeeds, and I see when it fails. Something that has really impacted my way of thinking is the level of importance any given shop is able to place on testing and validation. I’ve always been a big proponent of setting up a test system and following a very disciplined regimen to make sure it will work in production for any new projects, and then taking the lessons learned into production as standards. I know, I know – there’s never enough time to do things right like this. Yet the shops I see that do it have the same level of work that they output as the shops that don’t. They just make the time to do the testing and validation and create a standard that they will follow in production. And what I’ve found (surprise surprise) is that they have fewer production problems. OK, that might seem obvious – but I’ve actually tracked it and those places that do the testing and best practices really do save stress, time and trouble from that effort. We all think that’s a good idea, but we just “don’t have time”. OK – but from what I’m seeing, you can gain time if you spend a little up front. You may find that you’re actually already spending the same amount of time that you would spend in doing the testing, you’re just doing it later, at night, under the gun. Food for thought.  Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Storing a looong lookup table

  - by inquisitive

  Background The product i am working on has a very long lookup-table. the table contains static data and cannot be auto generated. there are about 500 rows and 10 columns. columns have mostly integers and strings. to complicate the matters, there are actually two such tables. every row in table-1 maps to zero-or-more rows in table-2. we use an SQLite database with two tables. the product installer places the SQLite file in the installation directory. the application is written in dot-net and we use ADO to load the data once on startup. now, the lookup table grows. in each release a month, we add about 10 new entries existing entries are adjusted. every release we fine tune existing entries. The problem a team of (10) developers work on the lookup table. Code goes in the SVN, but the little devil the SQLite does not. this prevents multiple developers to work on it. we do take regular backups of the file, but proper versioning is not possible. we never know who did the breaking change. the worse thing is we dont know if there is any change at all. diff'ing databases is tedious if not impossible. the tables are expected to grow quite large in years to come and we would need developers to work in parallel on it. the data is business critical. we need to be able to audit changes made to it. Question What would be a solution for the problems outlines above? one idea was to transform the whole thing to XML and treat it like just another source file. that way SVN can do the versioning and we can work in parallel. but the data shows relational behavior. with XML we loose the unique and foreign-key constraints. also we cant query it with sql like ease. any help here will be appreciated.

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• Boot error aftter clean Ubuntu 13.04 install: [Reboot and select proper boot device]

  - by IcarusNM

  I am having the same problem as this guy where a fresh Ubuntu install completes beautifully but will not boot. I get the ASUS (?) "Reboot and select proper boot device" error, first with Xubuntu 13.10 and after finally giving up there, and Xubuntu 13.4, I am back to regular Ubuntu 13.4. ASUS motherboard Z77, Intel chipset. Standard internal SATA 500GB HD. 64-bit. All-new hardware less than 3 months old. It was running Ubuntu 12.04LTC great until I tried this upgrade. I have re-installed from scratch every which way: with LVM, without LVM; with the default partitions, with my own partitions. With ext3 or ext4. Alongside; replace; upgrade. No difference. On the last two tries, I have booted afterward from the same USB stick, downloaded and run boot-repair, and now I guess I am off to the boot-repair support email with my URLs from that. It did all kinds of cool stuff but ultimately made no difference. I never got anything like this with Ubuntu 12.04. I've now probably re-installed Ubuntu 13.04 ten times slightly different ways. I finally found how to skip the language packs, so at least that sped things up! :) This starts from the ubuntu-13.04-desktop-amd64.iso and UNetbootin as suggested on the official instructions for USB thumb drive creation from OSX. That part all works fine (booting the USB on the PC and trying Ubuntu and/or installing from there on the PC HD.) I have no CD drive on this PC, but I suppose I could get one. I would rather find some Linux install that works from USB like I've always done. After running boot-repair twice, in the ASUS BIOS I now see three different UEFI boot options in the priority list, and they are all labeled exactly the same: ubuntu (P6: WDC WD5000AAKX-00U6AA0) Then there's a non-UEFI option: P6: WDC WD5000AAKX-00U6AA0 (476940MB) And a fifth option appeared after the first boot-repair: Windows Boot Manager (P6: WDC WD5000AAKX-00U6AA0) I have tried all 5 of these, and I get exactly the same error. I have never had Windows installed on this HD. ASUS is calling it Windows Boot Manaer but I presume that's a mistaken label for whatever boot-repair did. I can boot on USB and run GParted and it looks great. The partitions all look normal. I found another case of this online with no solution posted. I can't find much about it online. Needs a Master Boot Record wipe/redo?? I'm not sure how.

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• OSB unit testing, part 1 by Qualogy

  - by JuergenKress

  First you need to implement the simple bpel process like this : In my current project, I inherited a lot of OSB components that have been developed by (former) team members, but they all lack unit tests. This is a situation I really dislike, since this makes it much harder to refactor or bug-fix the existing code base. So, for all newly created components (and components I have to bug-fix) I strive to add unit tests. Of course, the unit tests will be created using my favourite testing tool: soapUI ! Unit of test The unit test should be created for the service composition, which in OSB terms should be the proxy service combination with its business service. Now, since you do not want to rely on any other services, you should provide mock services for all services invoked from your Component-Under-Test. In a previous article, I wrote about mocking your services in soapUI. While this approach would also be valid here, creating a mock service (and certainly deploying it on a separate WebServer) does violate one of the core principles of unit testing: to make your unit tests as self-contained as possible, i.e. not depending on any external components. In this article, I will show you how to achieve this by simply providing a mock response inside your unit test. Scenario The scenario I implement for testing is a simple currency converter; the external request consists of a from and a to currency, and an amount (in currency from). The service will perform an exchange rate lookup using the WebServiceX CurrencyConverter and return a response to the caller consisting of both the source and target currencies and amounts. For the purpose of unit testing, I will implement a mock response for the exchange rate lookup. Read the complete article here. SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Technorati Tags: Qualogy,OSB,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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• Deadlock Analysis in NetBeans 8

  - by Geertjan

  Lock contention profiling is very important in multi-core environments. Lock contention occurs when a thread tries to acquire a lock while another thread is holding it, forcing it to wait. Lock contentions result in deadlocks. Multi-core environments have even more threads to deal with, causing an increased likelihood of lock contentions. In NetBeans 8, the NetBeans Profiler has new support for displaying detailed information about lock contention, i.e., the relationship between the threads that are locked. After all, whenever there's a deadlock, in any aspect of interaction, e.g., a political deadlock, it helps to be able to point to the responsible party or, at least, the order in which events happened resulting in the deadlock. As an example, let's take the handy Deadlock sample code from the Java Tutorial and look at the tools in NetBeans IDE for identifying and analyzing the code. The description of the deadlock is nice: Alphonse and Gaston are friends, and great believers in courtesy. A strict rule of courtesy is that when you bow to a friend, you must remain bowed until your friend has a chance to return the bow. Unfortunately, this rule does not account for the possibility that two friends might bow to each other at the same time. To help identify who bowed first or, at least, the order in which bowing took place, right-click the file and choose "Profile File". In the Profile Task Manager, make the choices below: When you have clicked Run, the Threads window shows the two threads are blocked, i.e., the red "Monitor" lines tell you that the related threads are blocked while trying to enter a synchronized method or block: But which thread is holding the lock? Which one is blocked by the other? The above visualization does not answer these questions. New in NetBeans 8 is that you can analyze the deadlock in the new Lock Contention window to determine which of the threads is responsible for the lock: Here is the code that simulates the lock, very slightly tweaked at the end, where I use "setName" on the threads, so that it's even easier to analyze the threads in the relevant NetBeans tools. Also, I converted the anonymous inner Runnables to lambda expressions. package org.demo; public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s" + " has bowed to me!%n", this.name, bower.getName()); bower.bowBack(this); } public synchronized void bowBack(Friend bower) { System.out.format("%s: %s" + " has bowed back to me!%n", this.name, bower.getName()); } } public static void main(String[] args) { final Friend alphonse = new Friend("Alphonse"); final Friend gaston = new Friend("Gaston"); Thread t1 = new Thread(() -> { alphonse.bow(gaston); }); t1.setName("Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); }); t2.setName("Gaston bows to Alphonse"); t2.start(); } } In the above code, it's extremely likely that both threads will block when they attempt to invoke bowBack. Neither block will ever end, because each thread is waiting for the other to exit bow. Note: As you can see, it really helps to use "Thread.setName", everywhere, wherever you're creating a Thread in your code, since the tools in the IDE become a lot more meaningful when you've defined the name of the thread because otherwise the Profiler will be forced to use thread names like "thread-5" and "thread-6", i.e., based on the order of the threads, which is kind of meaningless. (Normally, except in a simple demo scenario like the above, you're not starting the threads in the same class, so you have no idea at all what "thread-5" and "thread-6" mean because you don't know the order in which the threads were started.) Slightly more compact: Thread t1 = new Thread(() -> { alphonse.bow(gaston); },"Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); },"Gaston bows to Alphonse"); t2.start();

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• How to configure a longer version Number in artifactory

  - by claudine

  The version-numbers for our jars have to be longer them x.x.x. We would rather need x.x.x.x to integrate some old-fashioned self-made mechanism. This is, because we tag our software with x.x.x and as soon as we have a delivery to a customer one specific jar has to be build exactly at this point of time to fit to another backend, which communicates with our program. For that reason this one jar has the version 2.3.4.1, when generated and in next delivery of the same Version it is build and named 2.3.4.2. Now artifactory cannot handle this an doesn't save more than x.x.x.2 in some cases. So we thought of maybe edit the regular expression in the maven repository layout (see attached Screenshot) Because testing the path in the field below shows, that it cannot handle the version number. Of course for the rest of our jars still x.x.x has to work.. For Example here is the maven-metadata.xml <?xml version="1.0" encoding="UTF-8"?> <metadata> <groupId>com.firm</groupId> <artifactId>someid</artifactId> <version>1.5.1</version> <versioning> <latest>1.5.1</latest> <release>1.5.1</release> <versions> <version>1.4.62</version> </versions> <lastUpdated>20120926073942</lastUpdated> </versioning> </metadata> The folder structure looks like: someid 1.4.62 1.4.62.1 1.4.62.2 1.4.62.3 If we deploy an new artifact version (1.4.62.1), the maven-metadata.xml contains the 1.4.62.1 version. But the artifactory overrides the version number (1.4.62.x) to (1.4.62) after an unspecified time. It seems that the artifactory only support major, minor and revision numbers, and deletes the buildnumber. Now we looking for a solution do disable this behavior. We use the JFrog Artifactory version 2.5.0 (rev. 13086). Any ideas, maybe? Thanks in andvance

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• JOB OF THE WEEK

  - by Maria Sandu

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* 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;} My name is Pascaline and I am the EMEA Solution Response Manager. I currently have a role open for a Benelux Solution Response Representative to jump-start his/her career in my international team of six people from all across Europe. Key for this exciting role is that you are curious to learn, like networking and constantly want to develop yourself. To help you with that, you will get extensive product trainings and workshops on all Oracle product lines and you will receive sales training. Further, you have the opportunity to get certified on Oracle products through online trainings and workshops. Every month you will also benefit from 1-on-1 sales coaching and regular coaching from me to help you grow and develop your career at Oracle! The role will include the follow-up of marketing events and online marketing activities with current Key Accounts in the Benelux. It is truly a pioneering role at Oracle as it is the first time that an employee will engage in business conversations about all lines of businesses and products ranges with Key Accounts. So are you interested to work in between marketing and sales? Do you want to work for a big IT multinational? Do you want to work abroad after you graduate and do you want to develop yourself? Then please visit this link for more information.

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• Oracle Data Protection: How Do You Measure Up? - Part 1

  - by tichien

  This is the first installment in a blog series, which examines the results of a recent database protection survey conducted by Database Trends and Applications (DBTA) Magazine. All Oracle IT professionals know that a sound, well-tested backup and recovery strategy plays a foundational role in protecting their Oracle database investments, which in many cases, represent the lifeblood of business operations. But just how common are the data protection strategies used and the challenges faced across various enterprises? In January 2014, Database Trends and Applications Magazine (DBTA), in partnership with Oracle, released the results of its “Oracle Database Management and Data Protection Survey”. Two hundred Oracle IT professionals were interviewed on various aspects of their database backup and recovery strategies, in order to identify the top organizational and operational challenges for protecting Oracle assets. Here are some of the key findings from the survey: The majority of respondents manage backups for tens to hundreds of databases, representing total data volume of 5 to 50TB (14% manage 50 to 200 TB and some up to 5 PB or more). About half of the respondents (48%) use HA technologies such as RAC, Data Guard, or storage mirroring, however these technologies are deployed on only 25% of their databases (or less). This indicates that backups are still the predominant method for database protection among enterprises. Weekly full and daily incremental backups to disk were the most popular strategy, used by 27% of respondents, followed by daily full backups, which are used by 17%. Interestingly, over half of the respondents reported that 10% or less of their databases undergo regular backup testing.  A few key backup and recovery challenges resonated across many of the respondents: Poor performance and impact on productivity (see Figure 1) 38% of respondents indicated that backups are too slow, resulting in prolonged backup windows. In a similar vein, 23% complained that backups degrade the performance of production systems. Lack of continuous protection (see Figure 2) 35% revealed that less than 5% of Oracle data is protected in real-time.  Management complexity 25% stated that recovery operations are too complex. (see Figure 1)  31% reported that backups need constant management. (see Figure 1) 45% changed their backup tools as a result of growing data volumes, while 29% changed tools due to the complexity of the tools themselves. Figure 1: Current Challenges with Database Backup and Recovery Figure 2: Percentage of Organization’s Data Backed Up in Real-Time or Near Real-Time In future blogs, we will discuss each of these challenges in more detail and bring insight into how the backup technology industry has attempted to resolve them.

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• Differences between a retail and wholesale website, and how difficult would it be to integrate them? [closed]

  - by kmy

  I was told to come here for some guidance, I know that my questions can be quite broad, but I just really want some kind of direction to go towards (links, articles, etc). So here it goes: For the past month I have been planning and started implementing a wholesale website, but plans got changed on me and I need to allow both retail and wholesale orders which will also depend on whether the account is a regular customer or also has a seller account. There are various types of products and it has been decided that I would use subcategories as tables to organize them and allow various specific item fields. So here are some of my specific questions: How different is the database structure for each item to be available for both wholesale and retail? Will it just be adding a quantity column and have two different pricing, or much more complicated? I am unaware if there's any price tables but would that be more difficult? They use Quickbooks POS software, how difficult/inefficient will it be to update inventory quantities if they have like 2000-4000 products? And what would be the best ways to extract the information and update the system? I know it export an excel spreadsheet so maybe a suggested php plugin for it? How difficult is this project in your professional opinion, and how big should a team usually be? (At the moment it is just me.) Projected time for planning, implementation, and quality assurance in accordance to team size? I am an entry level developer and I know that I do not have enough knowledge to direct myself on this website...What kind of web developer skills will I need to find to help me? (My company is willing to hire people to get this website done as fast as possible.) Also, what would be some great questionnaires to ask the product stakeholder about what he wants from the website? (He has made it clear he is neither computer or internet savvy...) Sorry for the amount of questions, I'm an entry level web developer and do not have a senior to look up to for guidance. I have knowledge in HTML, CSS, Javascript, jQuery, PHP, MySQL, phpMyAdmin. I have never used any frameworks like Zend, Magento, etc, and is doing this all from scratch. So far the website is built in an object oriented way, MVC architecture to the best of my abilities, but I have many doubts because I would really want to have this done right. If I have been unclear on some parts please tell me and I'll add more detail. I'm sure I'll have more additional questions later on, if anyone is open to that please tell me. Thanks in advance!

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• HAProxy reqrep remove URI on backend request

  - by Jim

  real quick question regarding HAProxy reqrep. I am trying to rewrite/replace the request that gets sent to the backend. I have the following example domain and URIs http://domain/web1 http://domain/web2 I want web1 to go to backend webfarm1, and web2 to go to webfarm2. Currently this does happen. However I want to strip off the web1 or web2 URI when the request is sent to the backend. Here is my haproxy.cfg frontend webVIP_80 mode http bind :80 #acl routing to backend acl web1_path path_beg /web1 acl web2_path path_beg /web2 #which backend use_backend webfarm1 if web1_path use_backend webfarm2 if web2_path default_backend webfarm1 backend webfarm1 mode http reqrep ^([^\ ]*)\ /web1/(.*) \1\ /\2 balance roundrobin option httpchk HEAD /index HTTP/1.1\r\nHost:\ example.com server webtest1 10.0.0.10:80 weight 5 check slowstart 5000ms server webtest2 10.0.0.20:80 weight 5 check slowstart 5000ms backend webfarm2 mode http reqrep ^([^\ ]*)\ /web2/(.*) \1\ /\2 balance roundrobin option httpchk HEAD /index HTTP/1.1\r\nHost:\ example.com server webtest1-farm2 10.0.0.110:80 weight 5 check slowstart 5000ms server webtest2-farm2 10.0.0.120:80 weight 5 check slowstart 5000ms If I go to http://domain/web1 or http://domain/web2 I see it in the error logs that the request on a server in each backend that the requst is for the resource /web1 or /web2 respectively. Therefore I believe there to be something wrong with my regular expression, even though I copied and pasted it from the Documentation. http://code.google.com/p/haproxy-docs/wiki/reqrep Summary: I'm trying to route traffic based on URI, however I want to strip the URI on the backend side. Go to http://domain/web1 -- backend request of / to webfarm1 Thank you! -Jim

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• WmiPrvSE memory leak on Windows 2008 *R2*

  - by MichaelGG

  I've seen references on Windows 2008 to WmiPrvSE leaks, but nothing about Windows 2008 R2. We're running R2 on top of Hyper-V (2008). We are also running NSClient++ for monitoring from opsview. Over time, WmiPrvSE.exe starts to use a lot of memory, causing memory alert issues (less than 10% free). VM has 2GB, WmiPrvSE consumes up to 500-600MB before I kill it. Killing the process doesn't seem to have any negative effect; it starts up again and I haven't noticed any problems. But after a day or two, it's back in the same situation. Any ideas on what to do? Resource Monitor doesn't show any Disk or Network IO by WmiPrvSE.exe. Just slowly climbing private memory... Edited to add: We aren't running clustering, or Windows System Resource Manager. The only regular WMI user I can guess is NSClient++, but we don't seem to have this problem on other servers.

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• How many bits for sequence number using Go-Back-N protocol.

  - by Mike

  Hi Everyone, I'm a regular over at Stack Overflow (Software developer) that is trying to get through a networking course. I got a homework problem I'd like to have a sanity check on. Here is what I got. Q: A 3000-km-long T1 trunk is used to transmit 64-byte frames using Go-Back-N protocol. If the propagation speed is 6 microseconds/km, how many bits should the sequence numbers be? My Answer: For this questions what we need to do is lay the base knowledge. What we are trying to find is the size of the largest sequence number we should us using Go-Back-N. To figure this out we need to figure out how many packets can fit into our link at a time and then subtract one from that number. This will ensure that we never have two packets with the same sequence number at the same time in the link. Length of link: 3,000km Speed: 6 microseconds / km Frame size: 64 bytes T1 transmission speed: 1544kb/s (http://ckp.made-it.com/t1234.html) Propagation time = 6 microseconds / km * 3000 km = 18,000 microseconds (18ms). Convert 1544kb to bytes = 1544 * 1024 = 1581056 bytes Transmission time = 64 bytes / 1581056bytes / second = 0.000040479 seconds (0.4ms) So then if we take the 18ms propagation time and divide it by the 0.4ms transmission time we will see that we are going to be able to stuff ( 18 / 0.4) 45 packets into the link at a time. That means that our sequence number should be 2 ^ 45 bits long! Am I going in the right direction with this? Thanks, Mike

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• Configure Postfix to send/relay emails Gmail (smtp.gmail.com) via port 587

  - by tom smith

  Hi. Using Centos 5.4, with Postfix. I can do a mail [email protected] subject: blah test . Cc: and the msg gets sent to gmail, but it resides in the spam folder, which is to be expected. My goal is to be able to generate email msgs, and to have them appear in the regular Inbox! As I understand Postfix/Gmail, it's possible to configure Postfix to send/relay mail via the authenticated/valid user using port 587, which would no longer have the mail be seen as spam. I've tried a number of parameters based on different sites/articles from the 'net, with no luck. Some of the articles, actually seem to conflict with other articles! I've also looked over the stacflow postings on this, but i'm still missing something... Also talked to a few people on IRC (Centos/Postfix) and still have questions.. So, i'm turning to Serverfault, once again! If there's someone who's managed to accomplish this, would you mind posting your main.cf, sasl-passwd, and any other conf files that you use to get this working! If I can review your config files, I can hopefully see where I've screwed up, and figure out how to correct the issue. Thanks for reading this, and any help/pointers you provide! ps, If there is a stackflow posting that speaks to this that I may have missed, feel free to point it out to me! -tom

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• How do I host node.js apps with pm2 without running them as root?

  - by jishi

  I have setup pm2 to run a node.js application, and I can successfully start it and it will resurrect upon reboot. However, the pm2 daemon is ran as root, which makes me think that all my node-scripts also runs as root? Even though I added them as a regular user in the system. The log files and stuff is created in the users home dir, /~/.pm2/logs, but the logs are owned by root. when I invoke pm2 startup (which handles the installation of the init.d script etc), it creates /etc/init.d/pm2-init.sh which looks like this: #!/bin/bash # chkconfig: 2345 98 02 # # description: PM2 next gen process manager for Node.js # processname: pm2 # ### BEGIN INIT INFO # Provides: pm2 # Required-Start: # Required-Stop: # Should-Start: # Should-Stop: # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: PM2 init script # Description: PM2 is the next gen process manager for Node.js ### END INIT INFO NAME=pm2 PM2=/usr/local/lib/node_modules/pm2/bin/pm2 NODE=/usr/local/bin/node export HOME="/root" start() { echo "Starting $NAME" $NODE $PM2 stopAll $NODE $PM2 resurrect } stop() { $NODE $PM2 dump $NODE $PM2 stopAll } restart() { echo "Restarting $NAME" stop start } status() { echo "Status for $NAME:" $NODE $PM2 list RETVAL=$? } case "$1" in start) start ;; stop) stop ;; status) status ;; restart) restart ;; *) echo "Usage: {start|stop|status|restart}" exit 1 ;; esac exit $RETVAL When I dump the processes (which is what it will use when resurrecting the processes), I see mentions of user "USER":"pi" but I don't think that it's actually run as user pi. Any thoughts?

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• Apache+LDAP auth on Ubuntu says "Can't contact LDAP server" while ldapsearch is perfect

  - by tw79

  Hi Gurus, I'm migrating from an existing apache+LDAP+mysql+php server to a new hardware platform. Old server is running Debian Lenny, which I have no config documentation available (was done by previous sysadmin); New server is running Ubuntu 10.04.2 LTS 32bit. After installing Apache and configured LDAP client on the new server, ldapsearch to the LDAP master (another dedicated server) returns results just fine. However, when using apache with https, logs complain that "Can't contact LDAP server". I'm authenticating using ldaps and can confirm that 636 port is open on the LDAP master. I can't understand why apache would fail while regular ldapsearch is working! Below is part of the virtualhost config: <Directory /> Options FollowSymLinks AllowOverride None #AuthLDAPEnabled on AuthType Basic AuthBasicProvider ldap AuthName "Private" AuthLDAPURL ldaps://master.ldap.organisation.com:636/ou=people,dc=organisation,dc=com?uid AuthzLDAPAuthoritative off require valid-user AddType application/x-httpd-php .php .phtml <IfModule mod_php4.c> php_flag magic_quotes_gpc Off php_flag track_vars On php_value include_path . </IfModule> </Directory> Any help/suggestion is very much appreciated!

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• Over 200 active requests like "OPTIONS * HTTP/1.0" 200 - "-" "Apache (internal dummy connection)"

  - by Stefan Lasiewski

  Some details: Webserver: Apache/2.2.13 (FreeBSD) mod_ssl/2.2.13 OpenSSL/0.9.8e OS: FreeBSD 7.2-RELEASE This is a FreeBSD Jail. I believe I use the Apache 'prefork' MPM (I run the default for FreeBSD). I use the default values for MaxClients (256) I have enabled mod_status, with "ExtendedStatus On". When I view /server-status , I see a handful of regular requests. I also see over 230 requests from the 'localhost', like these: 37-0 - 0/0/1 . 0.00 1510 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 38-0 - 0/0/1 . 0.00 1509 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 39-0 - 0/0/3 . 0.00 1482 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 40-0 - 0/0/6 . 0.00 1445 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 I also see about 2417 requests yesterday from the localhost, like these: Apr 14 11:16:40 192.168.16.127 httpd[431]: www.example.gov 127.0.0.2 - - [15/Apr/2010:11:16:40 -0700] "OPTIONS * HTTP/1.0" 200 - "-" "Apache (internal dummy connection)" The page at http://wiki.apache.org/httpd/InternalDummyConnection says "These requests are perfectly normal and you do not, in general, need to worry about them", but I'm not so sure. Why are there over 230 of these? Are these active connections? If I have "MaxClients 256", and over 230 of these connections, it seems that my webserver is dangerously close to running out of available connections. It also seems like Apache should only need a handful of these "internal dummy connections" We actually had two unexplained outages last night, and I am wondering if these "internal dummy connection" caused us to run out of available connections.

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• Avoiding DNS timeouts when a dns server fails

  - by user65124

  Hi there. We have a small datacenter with about a hundred hosts pointing to 3 internal dns servers (bind 9). Our problem comes when one of the internal dns servers becomes unavailable. At that point all the clients that point to that server start performing very slowly. The problem seems to be that the stock linux resolver doesn't really have the concept of "failing over" to a different dns server. You can adjust the timeout and number of retries it uses, (and set rotate so it will work through the list), but no matter what settings one uses our services perform much more slowly if a primary dns server becomes unavailable. At the moment this is one of the largest sources of service disruptions for us. My ideal answer would be something like "RTFM: tweak /etc/resolv.conf like this...", but if that's an option I haven't seen it. I was wondering how other folks handled this issue? I can see 3 possible types of solutions: Use linux-ha/Pacemaker and failover ips (so the dns IP VIPs are "always" available). Alas, we don't have a good fencing infrastructure, and without fencing pacemaker doesn't work very well (in my experience Pacemaker lowers availability without fencing). Run a local dns server on each node, and have resolv.conf point to localhost. This would work, but it would give us a lot more services to monitor and manage. Run a local cache on each node. Folks seem to consider nscd "broken", but dnrd seems to have the right feature set: it marks dns servers as up or down, and won't use 'down' dns servers. Any-casting seems to work only at the ip routing level, and depends on route updates for server failure. Multi-casting seemed like it would be a perfect answer, but bind does not support broadcasting or multi-casting, and the docs I could find seem to suggest that multicast dns is more aimed at service discovery and auto-configuration rather than regular dns resolving. Am I missing an obvious solution?

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• Nginx case-insensitive reverse proxy rewrites

  - by BrianM

  I'm looking to setup an nginx reverse proxy to make some upcoming server moves and load balanced implementations much easier within our apps. Since our servers are all IIS case sensitivity hasn't been an issue, but now with nginx it's becoming one for me. I am simply looking to do a rewrite regardless of case. Infrastructure notes: All backend servers are IIS Most services are WCF services I am trying to simplify the URLs so I can move services around as we continue to build out I can't set my location to case insensitive due to the following error: nginx: [emerg] "proxy_pass" cannot have URI part in location given by regular expression, or inside named location, or inside "if" statement, or inside "limit_except" block in /etc/nginx/sites-enabled/test.conf:101 The main part of my conf file where I am trying to handle the rewrite is as follows location /svc_test { proxy_set_header x-real-ip $remote_addr; proxy_set_header x-forwarded-for $proxy_add_x_forwarded_for; proxy_set_header host $http_host; proxy_pass http://backend/serviceSite/WFCService.svc; } location ~* /test { rewrite ^/(.*)/$ /svc_test/$1 last; } It's the /test location that I can't get figured out. If I call http://nginxserver/svc_test/help I get the WCF help page to display correctly and I can make all available REST calls. This HAS to be a boneheaded regex issue on my part, but I have tried several variations and all I can get are 404 or 500 errors from nginx. This is NOT rocket science so can someone point me in the right direction so I can look like an idiot and just move on?

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• Active RDP session over VPN getting disconnected

  - by Wandering Penguin

  I am having seemingly random disconnects of active RDP sessions (I am actively typing or otherwise interacting with the desktop) when connected over the VPN connection. The attempted to reconnect 1/20 pops up and proceeds all the way through 20 then drops. Once the session drops I can open a new session and connect again. This started happening about a week ago, The VPN connection is an IPSec VPN connection from a SonicWall NSA 2400. The NIC drivers are up to date. The VPN client is up to date. The firmware on the SonicWall is up to date (both regular and the early-release versions work the same). I have attempted to connect over three ISPs all with the same behavior. Two different workstations were used to test the VPN connection. The same behavior occurs when connecting to a domain workstation or server. If I am within the firewall I can connect to the same workstations and servers with the disconnect. The VPN connection has "enable fragmented packet handling" and "ignore DF (don't fragment) bit" set. Is there something I am missing in where I am looking for the problem?

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• What kind of “sysadmin stuff” should I show to students during a talk?

  - by Gregory Eric Sanderaon

  A teacher asked me If I could talk about my job as a linux sysadmin in his class. The course is called "Introduction to Operating systems" and i've been given 45 minutes to talk. The students are beginning their second year, so they've had a bit of experience with programming in different languages. What i'm like to do is show a series of hands-on examples of the kinds of things I do on a regular basis. I've already got a few ideas jotted down, but I'm afraid that they might be either too advanced or too simple for the students to appreciate. Another concern is that a topic might be too long to explain and use too much time overall. Here are a few ideas : Program deployment using version control (git in my case) filtering apache logs using grep, awk, uniq, tail A couple of bash scripts that i've made for various stuff on servers live montitoring (htop, iotop, iptraf) creating databases and assigning roles in mysql/postgresql So, are these ideas any good ? Do you have better ideas ? are the ideas too simple and should I go for more "advanced" stuff ?

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• OpenVpn Iptables Error

  - by Mook

  I mean real newbie - linux here.. Please help me configuring my openvpn through iptables. My main goal here is to open port for regular browsing (80, 443), email (110, 25), etc just like isp does but i want to block p2p traffic. So I will need to open only few port. Here are my iptables config # Flush all current rules from iptables # iptables -F iptables -t nat -F iptables -t mangle -F # # Allow SSH connections on tcp port 22 (or whatever port you want to use) # iptables -A INPUT -p tcp --dport 22 -j ACCEPT # # Set default policies for INPUT, FORWARD and OUTPUT chains # iptables -P INPUT DROP #using DROP for INPUT is not always recommended. Change to ACCEPT if you prefer. iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT # # Set access for localhost # iptables -A INPUT -i lo -j ACCEPT # # Accept packets belonging to established and related connections # iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # #Accept connections on 1194 for vpn access from clients #Take note that the rule says "UDP", and ensure that your OpenVPN server.conf says UDP too # iptables -A INPUT -p udp --dport 1194 -j ACCEPT # #Apply forwarding for OpenVPN Tunneling # iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT #10.8.0.0 ? Check your OpenVPN server.conf to be sure iptables -A FORWARD -j REJECT iptables -t nat -A POSTROUTING -o venet0 -j SNAT --to-source 100.200.255.256 #Use your OpenVPN server's real external IP here # #Enable forwarding # echo 1 > /proc/sys/net/ipv4/ip_forward iptables -A INPUT -p tcp --dport 25 -j ACCEPT iptables -A INPUT -p tcp --dport 26 -j ACCEPT iptables -A INPUT -p tcp --dport 80 -j ACCEPT iptables -A INPUT -p tcp --dport 110 -j ACCEPT iptables -A INPUT -p tcp --dport 443 -j ACCEPT iptables -L -v But when I connect to my vpn, i can't browsing and also got RTO on pinging yahoo, etc

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• Vista logs into black screen, "Application Error 0xc0000022" for explorer.exe

  - by IMAPC

  Whenever I attempt to log into a Windows Vista computer (the only account on it), I'm presented with a black screen & a cursor. I can open Task Manager, and from there I can launch applications. It seems to be using Aero Basic (instead of the full Aero which I had set as default before the problem started). When attempting to launch "explorer.exe" I get "explorer.exe - Application Error 'The application failed to initialize properly (0xc0000022). Click OK to terminate the application.'" Every now and then I get an error along the lines of "the application has failed to start because its side by side configuration is incorrect please see the application event log for more detail." I can boot into safe mode successfully, but I still get the black screen when I log into it in regular mode. I've tried most of the suggestions here, but did not work. I'm attempting to back up everything right now in case the only fix is to reinstall Windows. Has anyone seen this before?

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• Configuration management in support of scientific computing

  - by Sharpie

  For the past few years I have been involved with developing and maintaining a system for forecasting near-shore waves. Our team has just received a significant grant for further development and as a result we are taking the opportunity to refactor many components of the old system. We will also be receiving a new server to run the model and so I am taking this opportunity to consider how we set up the system. Basically, the steps that need to happen are: Some standard packages and libraries such as compilers and databases need to be downloaded and installed. Some custom scientific models need to be downloaded and compiled from source as they are not commonly provided as packages. New users need to be created to manage the databases and run the models. A suite of scripts that manage model-database interaction needs to be checked out from source code control and installed. Crontabs need to be set up to run the scripts at regular intervals in order to generate forecasts. I have been pondering applying tools such as Puppet, Capistrano or Fabric to automate the above steps. It seems perfectly possible to implement most of the above functionality except there are a couple usage cases that I am wondering about: During my preliminary research, I have found few examples and little discussion on how to use these systems to abstract and automate the process of building custom components from source. We may have to deploy on machines that are isolated from the Internet- i.e. all configuration and set up files will have to come in on a USB key that can be inserted into a terminal that can connect to the server that will run the models. I see this as an opportunity to learn a new tool that will help me automate my workflow, but I am unsure which tool I should start with. If any member of the community could suggest a tool that would support the above workflow and the issues specific to scientific computing, I would be very grateful. Our production server will be running Linux, but support for OS X would be a bonus as it would allow the development team to setup test installations outside of VirtualBox.

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