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• Backup data rate on Raspberry Pi maxing out at 5 Mb/s. Why?

  - by bastibe

  I set up my Raspberry Pi as a Time Machine, as documented here. At the moment, the Raspberry Pi is connected to my MacBook Pro using a direct Ethernet cable. Also, an external hard drive (laptop drive) is connected to the Raspberry Pi using the USB port. However, backups are pretty slow. Activity Monitor claims that the Network is transferring a very steady 5 Mb/s, where my Time Capsule is transferring up to 8 Mb/s with a lot of fluctuation. The Raspberry Pi self-reports (top) that its CPU is only half-used, with about equal parts afpd, usb-storage and jbd2/sda1-8. Thus, I think that the processing power of the Raspberry Pi does not seem to be the problem here. To me, this looks like there is some kind of bottleneck that maxes out at 5 Mb/s thus potentially having my backups run at less than their potential speed. To the best of my knowledge, this might be the afp-daemon, the usb-bus or the external hard drive. So, my question is, how could I identify the true culprit and what can I do about it?

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• Curios: What makes CPUs better than others? [closed]

  - by Zizma

  I have been wondering about this for a long while now and was hoping someone here could answer it pretty easily. If I was looking for the most powerful CPU what should I really be looking at? There are so many different parameters of a CPU and I am wanting to know what each thing does and what really matters. Basically this: What is the deal with cores? If I take using optimized applications out of the mix would it theoretically better to get quad core 1.0GHz CPU or a 1 core 4 GHz CPU? Also, what is the difference between maybe an Sandy Bridge CPU versus an Ivy Bridge CPU? If they both were had the same clock speed and number of cores would the Ivy Bridge perform better? Does an older Xeon with an equal clock speed and number of cores to a new i7 really perform worse/slower? Does size matter? Why would I go with a 22nm CPU over a 32nm when the size difference is so trivial? What about the cache? When does the cache come into play with performance?

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• How to achieve the following RTO & RPO with logshipping only using SQL Server?

  - by Jimmy Chandra

  Trying to come up with viable backup restore & logshipping solution for achieving the following: 15 minutes Recovery Point Objective (no more than 15 minutes data loss at any time) 5 minutes Recovery Time Objective (must be able to get the db up and running back by 5 minutes) Considering using logshipping only (which I think is kind of pushing it, but I want to know if anyone else know how to achieve this). Some other info for consideration: Using 40 Gbit / sec fiber channel between the primary and disaster recovery (DRC) sites The sites are about 600 km apart. At close of business, the amount of data generated is predicted to be about 150 MB/sec. Log backup is planned for every 5 min. Doing some rough calculation I came up w/ the following numbers: 40 Gbit / sec = 5 MB / sec @ 100% network efficiency. 5 MB / sec = 300 MB / min. @ 300 MB / min, the total amount of data that can be transfer considering the 5min RTO is about 1.5GB, but that will left no time for the actual backup and restore, so if we cut it down to 3min logshipping time, which equals to ~900 MB over 3 minutes at 100% network efficiency, that will left about 1 min backup time and 1 minute restore time. Currently don't have any information if the system being used is capable of restoring 900 MB in 1 min, but assume it can. for COB scenario... 150 MB/sec, and considering the 3 min logshipping time, which should equal to about 27 GB of data over 3 mins...??? I think this is where the SLA will break... since there is no way to transfer 27 GB of data over a 40Gbit/sec line in 3 min. Can I get someone else opinion? I am thinking database mirroring might be a better answer for this...

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• 16TB Volumes and SNMP On Windows

  - by John K

  As volumes larger than 16TB became more common, it was recognized that the 32 bit value used to report disk size and usage within the standard "HOST-RESOURCES" MIB in SNMP was not large enough to report the proper disk size. Net-SNMP seems to have addressed this issue by simply manipulating the value of "AllocationUnits" to maintain a 32 bit value for disk utilization (since total disk size/usage is equal to the 32 bit space value times the allocation unit), to allow for the calculation of a volume larger than 8/16TB. Presuming you don't have any reporting interest in the allocation unit, this seems like a fine solution. https://bugzilla.redhat.com/show_bug.cgi?id=654384 Window's built in SNMP service, however, seems to continue to suffer from this error, simply reporting the modulo of the used/assigned disk space, resulting in inaccurate disk size reporting. Is there a way to enable Windows to correctly report disk usage for volumes over 16TB? We attempted to simply install Net-SNMP 5.5 x64 and disable Windows SNMP service entirely, however this unfortunately did not fix our issue. I've seen people in the Cacti community mention simply scripting out a solution. Unfortunately, we're using Observium for quick and basic systems monitoring. If the issue can't be correct on the Window's side, can Observium be made to report custom MIBs?

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• Setup a new domain controller over a temporary VPN, but now Windows delays startup?

  - by Kris Anderson

  I'm migrating servers from colo locations to Amazon's VPC EC2 instances. If anyone hasn't worked with Amazon VPC before, VPN is a pain in the arse! Anyways, I setup a new server that acts as the domain controller for our Amazon VPC. In order to migrate all the user accounts from our existing domain controllers I manually connected to our colo VPN using my user account on the new Amazon EC2 machine. I was able to join the domain and the new Amazon server became another domain controller on our network. So far so good. The problem I'm having is that when booting the EC2 domain controller (which is no longer connected to the VPN so it can't communicate with the existing controllers), it takes a good 6-8 minuted before I can remote into the server (instead of the 1-2 minutes it should take). Also, during this time most of the services we also run (like IIS) also give 404 errors until the 6-8 minutes have passed. It's almost like the domain controller is attempting to reach the other domain controllers first and after 6-8 minutes it falls back to the one located on the local machine? I don't think that's what's happening though, because Server 2008 R2 doesn't have primary and backup domain controllers. They're all equal as far as Windows is concerned. For my network adapter I have only one DNS listed, 127.0.0.1, so it should be looking up the local domain controller and not the other domain controllers it connected to over VPN when VPN was enabled. In the server logs I'm seeing these warnings pop up during a reboot: The winlogon notification subscriber is taking long time to handle the notification event (CreateSession). The winlogon notification subscriber took 409 second(s) to handle the notification event (CreateSession). Any ideas on what's happening here? I would try removing the existing domain controllers from the new Amazon EC2 machine, but I still need to connect over VPN a few times to migrate some data between the servers, and I don't want that change being reflected back to the other domain controllers in our colo locations.

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• Copy New Files Only in .NET

  - by psheriff

  Recently I had a client that had a need to copy files from one folder to another. However, there was a process that was running that would dump new files into the original folder every minute or so. So, we needed to be able to copy over all the files one time, then also be able to go back a little later and grab just the new files. After looking into the System.IO namespace, none of the classes within here met my needs exactly. Of course I could build it out of the various File and Directory classes, but then I remembered back to my old DOS days (yes, I am that old!). The XCopy command in DOS (or the command prompt for you pure Windows people) is very powerful. One of the options you can pass to this command is to grab only newer files when copying from one folder to another. So instead of writing a ton of code I decided to simply call the XCopy command using the Process class in .NET. The command I needed to run at the command prompt looked like this: XCopy C:\Original\*.* D:\Backup\*.* /q /d /y What this command does is to copy all files from the Original folder on the C drive to the Backup folder on the D drive. The /q option says to do it quitely without repeating all the file names as it copies them. The /d option says to get any newer files it finds in the Original folder that are not in the Backup folder, or any files that have a newer date/time stamp. The /y option will automatically overwrite any existing files without prompting the user to press the "Y" key to overwrite the file. To translate this into code that we can call from our .NET programs, you can write the CopyFiles method presented below. C# using System.Diagnostics public void CopyFiles(string source, string destination){  ProcessStartInfo si = new ProcessStartInfo();  string args = @"{0}\*.* {1}\*.* /q /d /y";   args = string.Format(args, source, destination);   si.FileName = "xcopy";  si.Arguments = args;  Process.Start(si);} VB.NET Imports System.Diagnostics Public Sub CopyFiles(source As String, destination As String)  Dim si As New ProcessStartInfo()  Dim args As String = "{0}\*.* {1}\*.* /q /d /y"   args = String.Format(args, source, destination)   si.FileName = "xcopy"  si.Arguments = args  Process.Start(si)End Sub The CopyFiles method first creates a ProcessStartInfo object. This object is where you fill in name of the command you wish to run and also the arguments that you wish to pass to the command. I created a string with the arguments then filled in the source and destination folders using the string.Format() method. Finally you call the Start method of the Process class passing in the ProcessStartInfo object. That's all there is to calling any command in the operating system. Very simple, and much less code than it would have taken had I coded it using the various File and Directory classes. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free video on Silverlight entitled Silverlight XAML for the Complete Novice - Part 1.  

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• ADSL to T1, Is it worth it for us?

  - by Jack Hickerson

  The company I work for has roughly 45-55 simultaneous users (local and remote/VPN) logged in at a given time. We currently subscribe to an ADSL connection but we have been experiencing slower upload/download speeds as our number of users increase. So, I have a few questions with regards to upgrading our connection to a t1 line. I am aware that the number of channels on a t1 line are much greater then that of our current ADSL connection, but I have heard that the number of active users on a t1 line should be no greater than ~30 for optimal performance. I would think this statement is dependent on what each user was using the connection for and could change depending on this variable. That being said, I have tried to break down how the line would be used in our organization based on our major departments: Sales (~60% of total users) - Everyday surfing, email, research, occasional streaming media Marketing (~15% of total users) - Heavy reliance on uploading/downloading, streaming media, file sharing Other (~25% of total users) - email, rare use of any connection intensive activities. I have considered keeping the ADSL for our local users and dedicating the t1 to our remote users (or vice versa) but the cost is significantly higher then what we had hoped for. All factors being equal (# of users, frequency of downloads/uploads from our current activities) Would you suspect a significant performance increase in making the transition to a t1 line from our current ADSL line? What are your thoughts or recommendations?

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• Replicated MongoDB server slower than simple shards

  - by displayName

  I tried to compare the performance of a sharded configuration against a sharded and replicated configuration. The sharded configuration consists of 8 shards each running on three different machines thereby constituting a total of 24 shards. All 8 of these shards run in the same partition on each machine. The sharded and replicated version is 8 shards again just like plain sharding, and all 8 mongods run on the same partition in each machine. But apart from this, each of these three machine now run additional 16 threads on another partition which serve as the secondary for the 8 mongods running on other machines. This is the way I prepared a sharded and replicated configuration with data chunks having replication factor of 3. Important point to note is that once the data has been loaded, it is not modified. So after primary and secondaries have synchronized then it doesn't matter which one i read from. To run the queries, I use an entirely different machine (let's call it config) which runs mongos and this machine's only purpose is to receive queries and run them on the cluster. Contrary to my expectations, plain sharding of 8 threads on each machine (total = 3 * 8 = 24) is performing better for queries than the sharded + replicated configuration. I have a script written to perform the query. So in order to time the scripts, I use time ./testScript and see the result. I tried changing the reading preference for replicated cluster by logging to mongo of config and run db.getMongo().setReadPref('secondary') and then exit the shell and run the queries like time ./testScript. The questions are: Where am i going wrong in the replication? Why is it slower than its plain sharding version? Does the db.getMongo().ReadPref('secondary') persist when i leave the shell and try to perform the query? All the four machines are running Linux and i have already increased the ulimit -n to 2048 from initial value of 1024 to allow more connections. The collections are properly distributed and all the mongods have equal number of chunks. Goes without saying that indices in both configurations are the same.

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• Analytics in an Omni-Channel World

  - by David Dorf

  Retail has been around ever since mankind started bartering.  The earliest transactions were very specific to the individuals buying and selling, then someone had the bright idea to open a store.  Those transactions were a little more generic, but the store owner still knew his customers and what they wanted.  As the chains rolled out, customer intimacy was sacrificed for scale, and retailers began to rely on segments and clusters.  But thanks to the widespread availability of data and the technology to convert said data into information, retailers are getting back to details. The retail industry is following a maturity model for analytics that is has progressed through five stages, each delivering more value than the previous. Store Analytics Brick-and-mortar retailers (and pure-play catalogers as well) that collect anonymous basket-level data are able to get some sense of demand to help with allocation decisions.  Promotions and foot-traffic can be measured to understand marketing effectiveness and perhaps focus groups can help test ideas.  But decisions are influenced by the majority, using faceless customer segments and aggregated industry data points.  Loyalty programs help a little, but in many cases the cost outweighs the benefits. Web Analytics The Web made it much easier to collect data on specific, yet still anonymous consumers using cookies to track visits. Clickstreams and product searches are analyzed to understand the purchase journey, gauge demand, and better understand up-selling opportunities.  Personalization begins to allow retailers target market consumers with recommendations. Cross-Channel Analytics This phase is a minor one, but where most retailers probably sit today.  They are able to use information from one channel to bolster activities in another. However, there are technical challenges combining data silos so its not an easy task.  But for those retailers that are able to perform analytics on both sources of data, the pay-off is pretty nice.  Revenue per customer begins to go up as customers have a better brand experience. Mobile & Social Analytics Big data technologies are enabling a 360-degree view of the customer by incorporating psychographic data from social sites alongside traditional demographic data.  Retailers can track individual preferences, opinions, hobbies, etc. in order to understand a consumer's motivations.  Using mobile devices, consumers can interact with brands anywhere, anytime, accessing deep product information and reviews.  Mobile, combined with a loyalty program, presents an opportunity to put shopping into geographic context, understanding paths to the store, patterns within the store, and be an always-on advertising conduit. Omni-Channel Analytics All this data along with the proper technology represents a new paradigm in which the clock is turned back and retail becomes very personal once again.  Rich, individualized data better illuminates demand, allows for highly localized assortments, and helps tailor up-selling.  Interactions with all channels help build an accurate profile of each consumer, and allows retailers to tailor the retail experience to meet the heightened expectations of today's sophisticated shopper.  And of course this culminates in greater customer satisfaction and business profitability.

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• Four disks - RAID 10 or two mirrored pairs?

  - by ewwhite

  I have this discussion with developers quite often. The context is an application running in Linux that has a medium amount of disk I/O. The servers are HP ProLiant DL3x0 G6 with four disks of equal size @ 15k rpm, backed with a P410 controller and 512MB of battery or flash-based cache. There are two schools of thought here, and I wanted some feedback... 1). I'm of the mind that it makes sense to create an array containing all four disks set up in a RAID 10 (1+0) and partition as necessary. This gives the greatest headroom for growth, has the benefit of leveraging the higher spindle count and better fault-tolerance without degradation. 2). The developers think that it's better to have multiple RAID 1 pairs. One for the OS and one for the application data, citing that the spindle separation would reduce resource contention. However, this limits throughput by halving the number of drives and in this case, the OS doesn't really do much other than regular system logging. Additionally, the fact that we have the battery RAID cache and substantial RAM seems to negate the impact of disk latency... What are your thoughts?

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• Setting kernel memory for installing postgresql

  - by Matthieu Taymans

  My question is about setting the kernel shared memory for installing postgresql on mac osx 10.6.8. In the readme file of postgresql it is said: Shared Memory PostgreSQL uses shared memory extensively for caching and inter-process communication. Unfortunately, the default configuration of Mac OS X does not allow suitable amounts of shared memory to be created to run the database server. Before running the installation, please ensure that your system is configured to allow the use of larger amounts of shared memory. Note that this does not 'reserve' any memory so it is safe to configure much higher values than you might initially need. You can do this by editting the file /etc/sysctl.conf - e.g. % sudo vi /etc/sysctl.conf On a MacBook Pro with 2GB of RAM, the author's sysctl.conf contains: kern.sysv.shmmax=1610612736 kern.sysv.shmall=393216 kern.sysv.shmmin=1 kern.sysv.shmmni=32 kern.sysv.shmseg=8 kern.maxprocperuid=512 kern.maxproc=2048 Note that (kern.sysv.shmall * 4096) should be greater than or equal to kern.sysv.shmmax. kern.sysv.shmmax must also be a multiple of 4096. Once you have edited (or created) the file, reboot before continuing with the installation. If you wish to check the settings currently being used by the kernel, you can use the sysctl utility: % sysctl -a The database server can now be installed. I'm a real beginner with all this but need to instal postgresql for academic purposes do you know how i can set this kernel shared memory. Won't that be harmful for my system? Thank you in advance. Matthieu

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• Maximum limit of filepointer in php reached and not changeable

  - by mlaug

  I have a server with the current 5.3.x version installed. Since we are running a really simple and small server in php using sockets, that connects to a lot clients using sockets we need to raise the open file limit that has been already done on the server for the user, that runs the server #ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 29879 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 8192 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 29879 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited and we compiled php with --enable-fd-setsize=8192 still we are getting [19-Nov-2012 09:24:23 Europe/Berlin] PHP Warning: socket_select(): You MUST recompile PHP with a larger value of FD_SETSIZE. It is set to 1024, but you have descriptors numbered at least as high as 1024. --enable-fd-setsize=2048 is recommended, but you may want to set it to equal the maximum number of open files supported by your system, in order to avoid seeing this error again at a later date. once in a while in our logs. Anyone knows who to configure the unix server and php correctly to have that working? I found a bug, but that is related to 2006 and marked as "not a bug" https://bugs.php.net/bug.php?id=37025&edit=1

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• Growing Talent

  The subtitle of Daniel Coyles intriguing book The Talent Code is Greatness Isnt Born. Its Grown. Heres How. The Talent Code proceeds to layout a theory of how expertise can be cultivated through specific practices that encourage the growth of myelin in the brain. Myelin is a material that is produced and wraps around heavily used circuits in the brain, making them more efficient. Coyle uses an analogy that geeks will appreciate. When a circuit in the brain is used a lot (i.e. a specific action is repeated), the myelin insulates that circuit, increasing its bandwidth from telephone over copper to high speed broadband. This leads to the funny phenomenon of effortless expertise. Although highly skilled, the best players make it look easy. Coyle provides some biological backing for the long held theory that it takes 10,000 hours of practice to achieve mastery over a given subject. 10,000 hours or 10 years, as in, Teach Yourself Programming in Ten Years and others. However, it is not just that more hours equals more mastery. The other factors that Coyle identifies includes deep practice, practice which crucially involves drills that are challenging without being impossible. Another way to put it is that every day you spend doing only tasks you find monotonous and automatic, you are literally stagnating your brains development! Perhaps Coyles subtitle, needs one more phrase, Greatness Isnt Born. Its Grown. Heres How. And oh yeah, its not easy. Challenging yourself, continuing to persist in the face of repeated failures, practicing every day is not easy. As consultants, we sell our expertise, so it makes sense that we plan projects so that people can play to their strengths. At the same time, an important part of our culture is constant improvement, challenging yourself to be better. And the balancing contest ensues. I just finished working on a proof of concept (POC) we did for a project we are bidding on. Completely time boxed, so our team naturally split responsibilities amongst ourselves according to who was better at what. I must have been pretty bad at the other components, as I found myself working on the user interface, not my usual strength. The POC had a website frontend, and one thing I do know is HTML. After starting out in pure ASP.NET WebForms, I got frustrated as time was ticking, I knew what I wanted in HTML, but I couldnt coax the right output out of the ASP.NET controls. I needed two or three elements on the screen that were identical in layout, with different content. With a backup plan in  of writing the HTML into the response by hand, I decided to challenge myself a bit and see what I could do in an hour or two using the Microsoft submitted jQuery micro-templating JavaScript library. This risk paid off. I was able to quickly get the user interface up and running, responsive to the JSON data we were working with. I felt energized by the double win of getting the POC ready and learning something new. Opportunities  specifically like this POC dont come around often, but the takeaway is that while it wont be easy, there are ways to generate your own opportunities to grow towards greatness.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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• ArchBeat Link-o-Rama Top 10 for August 19-26, 2012

  - by Bob Rhubart

  The Top 10 most popular items shared via the OTN ArchBeat Facebook page for the week of August 19-26, 2012. Now Available: Oracle SQL Developer 3.2 (3.2.09.23) The latest release of Oracle SQl Developer includes UI enhancements, 12c database support, and bug fixes. ADF Tutorial Chapter 3: Creating a Master-Detail taskflow | Yannick Ongena Oracle ACE Yannick Ongena continues his ADF tutorial with a chapter devoted to view layer and using the data control to build pages that allow user to update reference data. GlassFish Community Event at JavaOne 2012 Don't miss out on this exclusive GlassFish Community Event on Sunday, September 30th from 11:00 a.m. – 1:00 p.m. in Moscone South. Register Now! Part of JavaOne 2012. Oracle BI 11g Book Authors – Podcast #9 | Art of Business Intelligence In this home-grown podcast, authors Christian Screen, Haroun Khan, and Adrian Ward talk about their new book, "Oracle Business Intelligence Enterprise Edition 11g: A Hands-On Tutorial," about their sessions at Oracle OpenWorld, and about their ORACLENERD t-shirts. Oracle Service Bus duplicate message check using Coherence | Jan van Zoggel "Giving the fact that every message on our ESB has an unique messageID element in the SOAP header we could store this on disk, database or in memory,"says Jan van Zoggel. "With the help of Oracle Coherence this last option, in memory, is relatively simple." Even simpler with Jan's detailed instructions. Oracle Technology Network Architect Day - Boston - Sept 12 There are easier ways to increase your IT brainpower. Skip the electrodes and register for Oracle Technology Network Architect Day in Boston, September 12, 2012. This free event includes 8 technical sessions, panel Q&A, roundtable discussions—and a free lunch. 8:00 a.m. – 5:00 p.m. at the Boston Marriott Burlington, One Burlington Mall Road, Burlington, MA 01803. Oracle BPM enable BAM | Peter Paul van de Beek "BAM enables you to make decisions based on real-time information gathered from your running processes," says Peter Paul van de Beek. "With BPMN processes you can use the standard Business Indicators that the BPM Suite offers you and use them to with BAM without much extra effort." Sample Application for Switching Application Module Data Sources | Andrejus Baranovskis A sample application and how-to guide from Oracle ACE Director and ADF expert Andrejus Baranovskis. ORCLville: Some Basic BI Thoughts "If we'd stop to consider what business intelligence really is, many of us might grow a different perspective about how we implement enterprise apps," says Oracle ACE Director Floyd Teter. "What if we implemented with an eye to what kind of information we'd like to get from our enterprise apps?" Oracle VM VirtualBox 4.1.20 released |Oracle's Virtualization Blog Oracle VM VirtualBox 4.1.20 was just released at the community and Oracle download sites, reports the Fat Bloke. This is a maintenance release containing bug fixes and stability improvements. Thought for the Day "The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds his castles in the air, from air, creating by exertion of the imagination. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures." — Frederick P. Brooks Source: SoftwareQuotes

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• Remote Socket Read In Multi-Threaded Application Returns Zero Bytes or EINTR (104)

  - by user39891

  Hi. Am a c-coder for a while now - neither a newbie nor an expert. Now, I have a certain daemoned application in C on a PPC Linux. I use PHP's socket_connect as a client to connect to this service locally. The server uses epoll for multiplexing connections via a Unix socket. A user submitted string is parsed for certain characters/words using strstr() and if found, spawns 4 joinable threads to different websites simultaneously. I use socket, connect, write and read, to interact with the said webservers via TCP on their port 80 in each thread. All connections and writes seems successful. Reads to the webserver sockets fail however, with either (A) all 3 threads seem to hang, and only one thread returns -1 and errno is set to 104. The responding thread takes like 10 minutes - an eternity long:-(. *I read somewhere that the 104 (is EINTR?), which in the network context suggests that ...'the connection was reset by peer'; or (B) 0 bytes from 3 threads, and only 1 of the 4 threads actually returns some data. Isn't the socket read/write thread-safe? I use thread-safe (and reentrant) libc functions such as strtok_r, gethostbyname_r, etc. *I doubt that the said webhosts are actually resetting the connection, because when I run a single-threaded standalone (everything else equal) all things works perfectly right, but of course in series not parallel. There's a second problem too (oops), I can't write back to the client who connect to my epoll-ed Unix socket. My daemon application will hang and hog CPU 100% for ever. Yet nothing is written to the clients end. Am sure the client (a very typical PHP socket application) hasn't closed the connection whenever this is happening - no error(s) detected either. Any ideas? I cannot figure-out whatever is wrong even with Valgrind, GDB or much logging. Kindly help where you can.

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• load average in top and procs in vmstat

  - by Mingfei.hua

  As far as I know, the load average in top is the numbers of precess(threads) in running or uninterrupted sleep status, So it should be equal to (procs-r +1 )+ procs-b in vmstat, but in practice, this two number always have big gap. Any wrongs in my understanding, appreciate so much if some guys give me some guide. top - 05:34:50 up 1 day, 20:56, 5 users, load average: 2.83, 2.67, 1.62 Tasks: 79 total, 1 running, 78 sleeping, 0 stopped, 0 zombie Cpu(s): 6.8%us, 1.8%sy, 0.0%ni, 91.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.4%st Mem: 1758000k total, 582636k used, 1175364k free, 103932k buffers Swap: 917500k total, 0k used, 917500k free, 180868k cached procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 0 0 0 1182524 103784 180860 0 0 1 9 6 53 7 2 91 0 0 0 0 0 1182524 103784 180860 0 0 0 36 70 117 0 0 100 0 0 0 0 0 1182516 103784 180860 0 0 0 0 73 132 0 1 100 0 0 0 0 0 1182516 103784 180860 0 0 0 0 60 127 0 0 100 0 0 1 0 0 1182516 103784 180860 0 0 0 0 62 102 0 0 100 0 0 0 0 0 1182628 103784 180860 0 0 0 0 289 238 1 2 97 0 0 2 0 0 1152160 103784 180892 0 0 0 8 1481 2371 54 12 34 0 0 1 0 0 1182192 103784 180860 0 0 0 0 681 834 19 4 78 0 0 0 0 0 1182200 103784 180860 0 0 0 0 80 147 0 1 100 0 0 0 0 0 1182200 103784 180860 0 0 0 0 53 107 0 0 100 0 0 0 0 0 1182208 103788 180856 0 0 0 72 64 123 0 0 100 1 0

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• Batch file to create many files with special characters

  - by MollyO

  Essential info: I have a file "DB_OUTPUT.TXT" with 304 lines that I need to turn into 304 files (one per line). Each line contains many special characters and may be up to tens of thousands of characters long. For these reasons, I'm having difficulty using a cmd.exe batch file (which limits the amount of input) and the echo command (which would try to execute each special character, short of me having to escape them all). I also have a file "DB_OUTPUT_FILENAMES.TXT" containing a distinct filename for each line-soon-to-be-file from "db_output.txt". So line 1 of DB_OUTPUT.TXT needs to be the body of a new file with a name equal to line 1 of DB_OUTPUT_FILENAMES.TXT. Extra info: As you may have guessed, DB_OUTPUT.TXT is output from a database; it contains 304 records with 6 or 7 columns at a fixed width with the last column being a SQL query. Each of these lines (db records) will be used as a script to create new database objects, which is why the special characters need to be preserved. Question: Is there a way to do this in a batch-like fashion? I'd be happy with either a Windows solution or a Linux one.

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• SSH sometimes screws up connection when terminal overflows?

  - by SeveQ

  I've got a problem with SSH on a Debian Lenny based server (it's a vHost within a Xen environment, booted on a Xen kernel). I hope someone can help me with this. The SSH connection seems somehow getting screwed up frequently when the terminal overflows (new lines beyond the bottom of the terminal, usually forcing it to scroll). The connection gets lost but not regularly disconnected. It nearly always happens when I do the following: an existing SSH connection gets disconnected (regularly) I order putty to reestablish the connection login-prompt appears at the very bottom of the putty terminal window I enter my login-name, press the enter key I'm asked for the password, I enter it, press the enter key and BOOM! Nothing more happens. I have to reconnect again. So it is reproducable. I'm not totally sure if the connection crashes before or after I enter the password. Furthermore it also happens when there is much text to be displayed (for example when I compile something or do an ls -l on a directory with many entries). Using 'screen', however, helps to reduces the frequency of occurence but doesn't solve the problem completely. It's occurence is independent from which terminal software I use. I mostly use putty but it also happens with other clients. I certainly hope somebody can help me solving this problem. Thanks in advance! //edit: I've just made a Wireshark trace of the ssh connection and there is nothing, I repeat, nothing different between the working and the failing connection (at least aside from frame numbers, ports and times that obviously can't be equal). This leads me to the assumption that the error has to happen on the server's side.

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• append $myorigin to localpart of 'from', append different domain to localpart of incomplete recipient address

  - by PJ P

  We have been having some trouble getting Postfix to behave in a very specific fashion in which sender and recipient addresses with only a localpart (i.e. no @domain) are handled differently. We have a number of applications that use mailx to send messages. We would like to know the username and hostname of the sending party. For example, if root sends an email from db001.company.local, we would like the email to be addressed from [email protected]. This is accomplished by ensuring $myorigin is set to $myhostname. We also want unqualified recipients to have a different domain appended. For example, if a message is sent to 'dbadmin' it should qualify to '[email protected]'. However, by the nature of Postfix and $myorigin, an unqualified recipient would instead qualify to [email protected]. We do not want to adjust the aliases on all servers to forward appropriately. (in fact, every possible recipient doesn't have an entry in /etc/passwd) All company employees have mailboxes on Exchange, which Postfix eventually routes to, and no local Linux/Unix mailboxes are used or access. We would love to tell our application owners to ensure they use a fully qualified email address for all recipients, but the powers that be dictate that any negligence must be accommodated. If we were to keep $myorigin equal to $myhostname, we could resolve this issue by having an entry such as the following in 'recipient_canonical_maps': @$myorigin @company.com However, unfortunately, we cannot use variables in these map files. We also want to avoid having to manually enter and maintain the actual hostname in 'recipient_canonical_maps' for each server. Perhaps once our servers are 'puppetized' we can dynamically adjust this file, but we're not there yet. After an afternoon of fiddling I've decided to reach out. Any thoughts? Thanks in advance.

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• Efficiently separating Read/Compute/Write steps for concurrent processing of entities in Entity/Component systems

  - by TravisG

  Setup I have an entity-component architecture where Entities can have a set of attributes (which are pure data with no behavior) and there exist systems that run the entity logic which act on that data. Essentially, in somewhat pseudo-code: Entity { id; map<id_type, Attribute> attributes; } System { update(); vector<Entity> entities; } A system that just moves along all entities at a constant rate might be MovementSystem extends System { update() { for each entity in entities position = entity.attributes["position"]; position += vec3(1,1,1); } } Essentially, I'm trying to parallelise update() as efficiently as possible. This can be done by running entire systems in parallel, or by giving each update() of one system a couple of components so different threads can execute the update of the same system, but for a different subset of entities registered with that system. Problem In reality, these systems sometimes require that entities interact(/read/write data from/to) each other, sometimes within the same system (e.g. an AI system that reads state from other entities surrounding the current processed entity), but sometimes between different systems that depend on each other (i.e. a movement system that requires data from a system that processes user input). Now, when trying to parallelize the update phases of entity/component systems, the phases in which data (components/attributes) from Entities are read and used to compute something, and the phase where the modified data is written back to entities need to be separated in order to avoid data races. Otherwise the only way (not taking into account just "critical section"ing everything) to avoid them is to serialize parts of the update process that depend on other parts. This seems ugly. To me it would seem more elegant to be able to (ideally) have all processing running in parallel, where a system may read data from all entities as it wishes, but doesn't write modifications to that data back until some later point. The fact that this is even possible is based on the assumption that modification write-backs are usually very small in complexity, and don't require much performance, whereas computations are very expensive (relatively). So the overhead added by a delayed-write phase might be evened out by more efficient updating of entities (by having threads work more % of the time instead of waiting). A concrete example of this might be a system that updates physics. The system needs to both read and write a lot of data to and from entities. Optimally, there would be a system in place where all available threads update a subset of all entities registered with the physics system. In the case of the physics system this isn't trivially possible because of race conditions. So without a workaround, we would have to find other systems to run in parallel (which don't modify the same data as the physics system), other wise the remaining threads are waiting and wasting time. However, that has disadvantages Practically, the L3 cache is pretty much always better utilized when updating a large system with multiple threads, as opposed to multiple systems at once, which all act on different sets of data. Finding and assembling other systems to run in parallel can be extremely time consuming to design well enough to optimize performance. Sometimes, it might even not be possible at all because a system just depends on data that is touched by all other systems. Solution? In my thinking, a possible solution would be a system where reading/updating and writing of data is separated, so that in one expensive phase, systems only read data and compute what they need to compute, and then in a separate, performance-wise cheap, write phase, attributes of entities that needed to be modified are finally written back to the entities. The Question How might such a system be implemented to achieve optimal performance, as well as making programmer life easier? What are the implementation details of such a system and what might have to be changed in the existing EC-architecture to accommodate this solution?

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• Insufficient channel capacity of 1GBit

  - by Roman S

  There is a Caching Server (Varnish): it receives data from Amazon S3 on request, saves it for some time and gives it to the client. We have encountered the problem of insufficient channel capacity of 1GBit. Peak load within 4 hours completely chokes the channel. Server performance is sufficient for now. Approximately 4.5TB of data are transmitted per day. More than 100TB are accumulated per month. The first thought that comes to mind is simply to add one more 1GBit port and sleep peacefully until 2GBit are not enough (it may happen quite quickly) or one server is not able to handle it. And then we just need to add new Caching Servers. But now we need a Load Balancer, which will send requests on one and the same URL, always on one and the same server (to avoid multiple copies of the same cached objects). Here are the questions: Does a Balancer need a band equal to sum of all bands of Caching Servers? What shall we do in case there are no ports in a Balancer? Should we add more Balancers or solve the problem by means of Round robin DNS? What are the standard approaches to such problems? Can anyone advise hosting-companies, which can solve this problem? We are interested in American and European markets.

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• Let Me Show You Something: Instagram, Vine and Snapchat for Brands

  - by Mike Stiles

  While brands are well aware of how much more impactful images are than text-only posts on social channels, today you’re additionally being presented with platform after additional platform for hosting, doctoring and sharing photos and videos.  Can you play in every sandbox? And if you do, can you be brilliant on all of them? As has usually been the case, so far brands are sticking their toes into new platforms while not actually committing to them, or strategizing for them, or resourcing them. TrackMaven found of the 123 F500 companies using Instagram, only 22% of them are active on it. Likewise, research from Simply Measured found brands are indeed jumping in, with the number establishing a presence on Instagram up 55% over the past year. Users want them there…brand engagement has exploded 350%, and over 1/3 of the top brands have at least 10,000 followers. BUT…the top 10 brands are generating 33% of all posts, reaping 83% of all engagement. Things are also growing on Twitter’s Vine, the 6-second looping video app that hit 40 million users in August. The 7th Chamber says 5 tweets a second contain a Vine link. Other studies say branded Vines are 4 times more likely to be shared and seen than rank-and-file branded videos. Why? Users know that even if a video is pure junk, they won’t get robbed of too much of their valuable time. Vine is always upgrading so you can make sure your videos are worth viewers’ time. You can now edit videos, and save & work on several projects concurrently. What you can’t do is upload a finely crafted video into Vine, but you can do that with Instagram. The key to success? Same as with all other content; make it of value. Deliver a laugh or a lesson or both. How-to, behind the scenes peeks, contests, demos, all make sense in the short video format. Or follow Nash Grier’s example, which is to just have fun with and connect to your viewers, earning their trust that your next Vine will be as good as the last. Nash is only 15, has over 1.4 million followers, and adds about 100,000 a week. He broke out when one of his videos was re-Vined by some other kid with 300,000 followers. Make good stuff, get it in front of influencers, and your brand Vines could break out as well. Then there’s Snapchat, the “this photo will self destruct” platform. How can that be of use to brands besides offering coupons that really expire? The jury is out. But with an audience of over 100 million and a valuation of $800 million, media-with-a-time-limit is compelling. Now there’s “Snapchat Stories” that can last 24 hours and be shared to the public at large. You might be able to capitalize on how much more focus gets put on content when there’s a time limit on its availability. The underlying truth to all of this is, these are all tools. Very cool, feature rich tools, but tools. You can give the exact same art kit to 5 different people and you’d get back 5 very different works, ranging from worthless garbage to masterpiece. Brands are being called upon to be still and moving image artists. That’s what your customers are used to seeing, from a variety of sources. Commit to communicating with them accordingly. @mikestiles Photo: stock.xchng

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• Win2008: Boot from mirrored dynamic disk fails!

  - by Daniel Marschall

  Hello. I am using Windows Server 2008 R2 Datacenter and I got two 1.5TB S-ATA2 hard disks installed and I want to make a soft raid. (I do know the disadvantages of softraid vs. hardraid) I have following partitions on Disk 0: (1) Microsoft Reserved 100 MB (dynamic), created during setup (2) System Partition 100 GB (dynamic) (3) Data partition, 1.2TB (dynamic) I already mirrored these contents to Disk 1. Its contents are: (1) System partition mirror, 100 GB (dynamic) (2) Data partition, 1.2 TB mirror (dynamic) (3) Unusued 100 MB (dynamic) -- is from "MSR" of Disk 0, created during setup. Since data and system partition are mirrored, I expect that my system works if disk 0 would fail. But it doesn't. If I force booting on disk 0: Works (I get the 2 bootloader screen) If I force booting on disk 1 (F8 for BBS), nothing happens. I got a blank black screen with the blinking caret. I already made disk1/partition1 active with diskpart, but it still does not boot from this drive. Please help. Both partitions are in "MBR" partition style. They look equal, except the missing "MSR" partition at the partition beginning (which seems to be not relevant to booting). Regards Daniel Marschall

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• Fun with Python

  - by dotneteer

  I am taking a class on Coursera recently. My formal education is in physics. Although I have been working as a developer for over 18 years and have learnt a lot of programming on the job, I still would like to gain some systematic knowledge in computer science. Coursera courses taught by Standard professors provided me a wonderful chance. The three languages recommended for assignments are Java, C and Python. I am fluent in Java and have done some projects using C++/MFC/ATL in the past, but I would like to try something different this time. I first started with pure C. Soon I discover that I have to write a lot of code outside the question that I try to solve because the very limited C standard library. For example, to read a list of values from a file, I have to read characters by characters until I hit a delimiter. If I need a list that can grow, I have to create a data structure myself, something that I have taking for granted in .Net or Java. Out of frustration, I switched to Python. I was pleasantly surprised to find that Python is very easy to learn. The tutorial on the official Python site has the exactly the right pace for me, someone with experience in another programming. After a couple of hours on the tutorial and a few more minutes of toying with IDEL, I was in business. I like the “battery supplied” philosophy that gives everything that I need out of box. For someone from C# or Java background, curly braces are replaced by colon(:) and tab spaces. Although I tend to miss colon from time to time, I found that the idea of tab space is actually very nice once I get use to them. I also like to feature of multiple assignment and multiple return parameters. When I need to return a by-product, I just add it to the list of returns. When would use Python? I would use Python if I need to computer anything quick. The language is very easy to use. Python has a good collection of libraries (packages). The REPL of the interpreter allows me test ideas quickly before committing them into script. Lots of computer science work have been ported from Lisp to Python. Some universities are even teaching SICP in Python. When wouldn’t I use Python? I mostly would not use it in a managed environment, such as Ironpython or Jython. Both .Net and Java already have a rich library so one has to make a choice which library to use. If we use the managed runtime library, the code will tie to the particular runtime and thus not portable. If we use the Python library, then we will face the relatively long start-up time. For this reason, I would not recommend to use Ironpython for WP7 development. The only situation that I see merit with managed Python is in a server application where I can preload Python so that the start-up time is not a concern. Using Python as a managed glue language is an over-kill most of the time. A managed Scheme could be a better glue language as it is small enough to start-up very fast.

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• Ubiquitous BIP

  - by Tim Dexter

  The last number I heard from Mike and the PM team was that BIP is now embedded in more than 40 oracle products. That's a lot of products to keep track of and to help out with new releases, etc. Its interesting to see how internal Oracle product groups have integrated BIP into their products. Just as you might integrate BIP they have had to make a choice about how to integrate. 1. Library level - BIP is a pure java app and at the bottom of the architecture are a group of java libraries that expose APIs that you can use. they fall into three main areas, data extraction, template processing and formatting and delivery. There are post processing capabilities but those APIs are embedded withing the template processing libraries. Taking this integration route you are going to need to manage templates, data extraction and processing. You'll have your own UI to allow users to control all of this for themselves. Ultimate control but some effort to build and maintain. I have been trawling some of the products during a coffee break. I found a great post on the reporting capabilities provided by BIP in the records management product within WebCenter Content 11g. This integration falls into the first category, content manager looks after the report artifacts itself and provides you the UI to manage and run the reports. 2. Web Service level - further up in the stack is the web service layer. This is sitting on the BI Publisher server as a set of services, runReport and scheduleReport are the main protagonists. However, you can also manage the reports and users (locally managed) on the server and the catalog itself via the services layer.Taking this route, you still need to provide the user interface to choose reports and run them but the creation and management of the reports is all handled by the Publisher server. I have worked with a few customer on this approach. The web services provide the ability to retrieve a list of reports the user can access; then the parameters and LOVs for the selected report and finally a service to submit the report on the server. 3. Embedded BIP server UI- the final level is not so well supported yet. You can currently embed a report and its various levels of surrounding  'chrome' inside another html based application using a URL. Check the docs here. The look and feel can be customized but again, not easy, nor documented. I have messed with running the server pages inside an IFRAME, not bad, but not great. Taking this path should present the least amount of effort on your part to get BIP integrated but there are a few gotchas you need to get around. So a reasonable amount of choices with varying amounts of effort involved. There is another option coming soon for all you ADF developers out there, the ability to drop a BIP report into your application pages. But that's for another post.

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