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• Dropped impression 25 days after restructure

  - by Hamid

  Our website is a non English property related website (moshaver.com) which is similar to rightmove.co.uk. On September 2012 our website was adversely affected by Panda causing our Google incoming clicks to drop from around 3000 clicks to less than a thousand. We were hoping that Google will eventually realize that we are not a spam website and things will get better. However, in August 2013 we were almost sure that we needed to do something, so we started to restructure our web content. We used the canonical tag to remove our search results and point to our listing pages, using the noindex tag to remove it from our listing pages which does not have any properties at the moment. We also changed title tags to more friendly ones, in addition to other changes. Our changes were effective on 10th August. As shown in the graph taken from Google Analytics Search Engine Optimization section, these changes has resulted in an increase in the number of times Google displayed our results in its search results. Our impressions almost doubled starting 15th August. However, as the graph shows, our CTR dropped from this date from around 15% to 8%. This might have been because of our changed title tags (so people were less likely to click on them), or it might be normal for increased impressions. This situation has continued up until 10th September, when our impressions decreased dramatically to less than a thousand. This is almost 30% of our original impressions (before website restructure) and 15% of the new impressions. At the same time our impressions has increased dramatically to around 50%. I have two theories for this increase. The first one is that these statistics are less accurate for lower impressions. The second one is that Google is now only displaying our results for queries directly related to our website (our name, our url), and not for general terms, such as "apartments in a specific city". The second theory also explains the dramatic decrease in impression as well. After digging the analytic data a little more, I constructed the following table. It displays the breakdown of our impressions, clicks and ctr in different Google products (web and image) and in total. What I understand from this table is that, most of our increased impressions after restructure were on the image search section. I don't think users of search would be looking for content in our website. Furthermore, it shows that the drop in our web search ctr, is as dramatic of the overall ctr (-30% in compare to -60%) . I thought posting it here might help you understand the situation better. Is it possible that Google has tested our new structure for 25 days, and then decided to decrease our impressions because of the the new low CTR? Or should we look for another factor? If this is the case, how long does it usually take for Google to give us another chance? It has been one month since our impressions has dropped.

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• 45 minutes to talk about C# [closed]

  - by Philip

  I have the opportunity to give a 45 minute talk on C# in the theory of programming languages class I'm taking. The college teaches Java almost exclusively, so that's what all the students are most familiar with. (There's a little C, assembly, Prolog and LISP as well.) I decide what to talk about. It seems to me the best approach is to focus on a few of the big, obvious differences between C# and Java. I don't intend it to be a recommendation to use C# -- there are reasons to use each, mostly because of their ecosystems. So I want to focus on C# as a language. I don't want to go too fast and end up listing a whole bunch of features without showing their usefulness. My current plan is this: Functions as first class objects. This is, in my opinion, one of the biggest differences between C# and Java. The professor briefly mentioned this notion and showed a LISP example, but many of the students have probably never used it. I can show real world examples where it's made my code more readable. Lambda expressions as concise syntax for anonymous functions. Obviously with examples to show how this is useful. The real hit-home examples will be at the end when it's combined with the rest. I don't see an advantage to first showing the old delegate syntax and then replacing it with lambdas -- most of us won't have ever seen delegates anyway so it would just be confusing. The yield keyword and how it's different from returning an array. I have the impression that a lot of C# developers aren't familiar with how to use this. It will likely be very foreign to Java developers. I have some examples from my own work where it was really useful, such as iterating over a tree traversal, or iterating over neighbors in a graph where the neighbors aren't stored in memory. In both cases, doing it in Java would likely mean returning a complete list -- with yield I can stop iterating if I find what I want early on, without using memory for superfluous lists or arrays. Extension methods as a way to write implementation on interfaces. We'll all be familiar with how interfaces don't allow method implementation, and how this leads to code duplication. I'll show a specific example of this and how the extension method can solve the problem. Demonstrate how the above can be combined by implementing some simple Linq methods and using them. Where, Select, First, maybe more depending on how much time is left. Ideas on which ones might 'hit home' the best? There are other things I could talk about such as generics, value types, properties and more. I haven't yet though of good ways to incorporate these. In the case of generics and value types, the advantages might not be obvious or as relevant. Properties are obviously useful, particularly since we're taught strict JavaBeans here, but I don't know if I could integrate it with the "path to Linq" discussion above without it feeling tacked on. So I'm looking for thoughts on how to talk about C#, and what to talk about. Even minor details. I'm sure there are more experienced C# developers than me here who have good insight about what's really important in the language, and what would miss the point.

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• MIX 2010 Covert Operations Day 3

  - by GeekAgilistMercenary

  I rolled over to the Mandalay for breakfast.  There I met a couple guys that were really excited about the new Windows 7 Phone.  They, as I, are also hopeful that the phone really gets a big push and some penetration into the market.  Not because we don’t like any other of the phones, but because this phone is so much better in many ways.  From a developer's perspective creating applications in Windows 7 Mobile will be vastly superior in ease, capabilities, and other aspects.  The architectural, existing code base, examples, and provisions to create things on the 7 Mobile Device are already existing as of RIGHT NOW.  There is no reason, except for fickle market conditions, for this phone to not just explode onto the market.  But alas, I won't hold my breath. Day three keynote had a whole new slew of things provided.  It also seemed that things got a lot more technical on this second keynote.  The oData was one of the very technical bits, yet it included almost no code.  Starting with a Netflix example and all the way to the Codename "Dallas" effort the oData Services provide some expansive possibilities. A mash up going 4 ways was then shown for finding a movie, finding local places to have a viewing, and information about the movie and were to prospectively find and buy additional movie bits.  The display was of course, in a Windows 7 Mobile device with literally a click to view each set of data.  The backend and the front end of this was beautifully smooth. The Dallas Project has a lot of potential for analytics in dashboard and scorecard creation also.  If there is a need or reason to provide data to a vast and wide range of clients, Dallas is a prime example of how to do that. Azure Clouds After the main keynote I checked out (while developing a working WPF & Silverlight Application for work) the session on deploying ASP.NET Applications, services, etc, into the cloud.  The session was pretty good, but I'll admit I got a little unfocused from it a few times.  It is after all hard to do two things at one time. I did take note that the cloud still is a multiple step process for deploying to.  This is a good thing and a bad thing.  There needs to be more checks and verifications when deploying something into the cloud just for technical reasons.  However, I feel that there should be some streamlining to the process.  Going back and forth between web and Visual Studio as the interface also seems kind of clunky.  Deployment should be able to be completed from within Visual Studio in my perspective.  Overall, the cloud is getting more and more impressive in function as well as theory. That's it from me so far on the third day of MIX.  I'll be note taking and studying hard to have more good tidbits to provide. Thanks for reading, if you're curious about more of my writing, check out this original entry at my other blog Agilist Mercenary.

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• SQL SERVER – #TechEdIn – Presenting Tomorrow on Speed Up! – Parallel Processes and Unparalleled Performance at TechEd India 2012

  - by pinaldave

  Performance tuning is always a very hot topic when it is about SQL Server. SQL Server Performance Tuning is a very challenging subject that requires expertise in Database Administration and Database Development. I always have enjoyed talking about SQL Server Performance tuning subject. However, in India, it’s actually the very first time someone is presenting on this interesting subject, so this time I had the biggest challenge to present this session. Frequently enough, we get these two kind of questions: How to turn off parallelism as it is reducing performance? How to turn on parallelism as I want more performance? The reality is that not everyone knows what exactly is needed by their system. In this session, I have attempted to answer this very question. I’ve decided to provide a balanced view but stay away from theory, which leads us to say “It depends”. The session will have a clear message about this towards its end. Deck Details Slides: 45+ Demos: 7+ Bonus Quiz: 5 Images: 10+ Session delivery time: 52 Mins + 8 Mins of Q & A I have presented this session a couple of times to my friends and so far have received good feedback. Oftentimes, when people hear that I am going to present 45 slides, they all say it is too much to cover. However, when I am done with the session the usual reaction is that I truly gave justice to those slides. Action Item Here are a few of the action items for all of those who are going to attend this session: If you want to attend the session, just come early. There’s a good chance that you may not get a seat because right before me, there is a session from SQL Guru Vinod Kumar. He performs a powerful delivery of million concepts in just a little time. Quiz. I will be asking few questions during the session as well as before the session starts. If you get the correct answer, I will give unique learning material for you. You may not want to miss this learning opportunity at any cosst. Session Details Title: Speed Up! – Parallel Processes and Unparalleled Performance (Add to Calendar) Abstract: “More CPU, More Performance” – A  very common understanding is that usage of multiple CPUs can improve the performance of the query. To get a maximum performance out of any query, one has to master various aspects of the parallel processes. In this deep-dive session, we will explore this complex subject with a very simple interactive demo. Attendees will walk away with proper understanding of CX_PACKET wait types, MAXDOP, parallelism threshold and various other concepts. Date and Time: March 23, 2012, 12:15 to 13:15 Location: Hotel Lalit Ashok - Kumara Krupa High Grounds, Bengaluru – 560001, Karnataka, India. Add to Calendar Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• How to manage processes-to-CPU cores affinities ?

  - by Philippe

  I use a distributed user-space filesystem (GlusterFS) and I would like to be sure GlusterFS processes will always have the computing power they need. Each execution node of my grid have 2 CPU, with 4 cores per CPU and 2 threads per core (16 "processors" are seen by Linux). My goal is to guarantee that GlusterFS processes have enough processing power to be reliable, responsive and fast. (There is no marketing here, just the dreams of a sysadmin ;-) I consider two main points : GlusterFS processes I/O for data access (on local disks, or remote disks) I thought about binding the Linux Kernel and GlusterFS instances on a specific "processor". I would like to be sure that : No grid job will impact the kernel and the GlusterFS instances Researchers jobs won't be affected by system processes (I'd like to reserve a pool of cores to job execution and be sure that no system process will use these CPUs) But what about I/O ? As we handle a huge amount of data (several terabytes), we'll have a lot of interuptions. How can I distribute these operations on my processors ? What are the "best practices" ? Thanks for your comments!

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• Being a more attractive job candidate - Certs XOR Degree

  - by Zephyr Pellerin

  I'm currently working in an IT position, where I do helpdesk stuff, and predominantly security related issues/consulting (In the loosest sense of the term) In-House and for Service-Contract clients (as the only/acting CCSP [I guess I should say only person with Cisco experience] in my organization). I've professionally written Kernel Mode drivers for a gaming company. Among other things that I'm proud to put on a resume. I think of myself as very reasonably qualified as a System Administrator, With excellent Cisco experience, among other things I think would make a good addition to almost any IT staff in need of a new employee. However, Something has always tripped me up - Human Resources. Let me explain, I decided to skip the university route - I'm immensely glad that I did, The computer science graduates that I've met and work with rarely know much of anything about Computers (Until they gain some 'real' experience), Even when asked about Theoretical Computing fundamentals they can rattle something off about Turing Completeness but rarely do they understand the mathematical underpinnings. In short, I think instead of going to college, I'd rather pick up some real world experience. However, Apparently, Employers rarely think the same way. A quick perusal of jobs through the standard job search engine yields nothing short of a conspiracy to exclude anyone without 'A Bachelors Degree in Computer Science or Equivalent'. Interviews I've had in the past have almost always been entangled with - 1. My Age (Which I can't really change) and 2. Lack of Degree. Employers frequently disregard the CCNA/CCSP, The experience I've gained through internships, My extensive experience in x86 assembly and C, among so many other things I like to think are valuable to employers - In lieu of the fact that I don't have a piece of paper. So, AS AN EMPLOYER - Is it even worth working on my CCIE? Or should I pad my resume with certifications that are easier to acquire (Like CISSP, MSCE, Network+, etc.). Or should I ditch the whole idea and head back to get a Mathematics or CS degree?

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• Cannot install git-core using macports

  - by robUK

  Hello, Snow Leopard 10.6.4 mac ports 1.9.1 I have just installed macports and I want to install git-core. However, I get the following errors: ---> Computing dependencies for git-core ---> Dependencies to be installed: python26 db46 gdbm readline sqlite3 rsync popt ---> Building db46 Error: Target org.macports.build returned: shell command failed Log for db46 is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_databases_db46/main.log Error: The following dependencies failed to build: python26 db46 gdbm readline sqlite3 rsync popt Error: Status 1 encountered during processing. To report a bug, see <http://guide.macports.org/#project.tickets> I have tried doing a port selfupdate and a port clean all and then trying to install again. But still get the same problem. I have also tried install the dependent db46 on its own. Here is the log message: :error:build Target org.macports.build returned: shell command failed :debug:build Backtrace: shell command failed while executing "command_exec build" (procedure "portbuild::build_main" line 8) invoked from within "$procedure $targetname" :info:build Warning: the following items did not execute (for db46): org.macports.activate org.macports.build org.macports.destroot org.macports.install This is my first time using mac ports. Many thanks for any suggestions.

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• Programmatically disclosing a node in af:tree and af:treeTable

  - by Frank Nimphius

  A common developer requirement when working with af:tree or af:treeTable components is to programmatically disclose (expand) a specific node in the tree. If the node to disclose is not a top level node, like a location in a LocationsView -> DepartmentsView -> EmployeesView hierarchy, you need to also disclose the node's parent node hierarchy for application users to see the fully expanded tree node structure. Working on ADF Code Corner sample #101, I wrote the following code lines that show a generic option for disclosing a tree node starting from a handle to the node to disclose. The use case in ADF Coder Corner sample #101 is a drag and drop operation from a table component to a tree to relocate employees to a new department. The tree node that receives the drop is a department node contained in a location. In theory the location could be part of a country and so on to indicate the depth the tree may have. Based on this structure, the code below provides a generic solution to parse the current node parent nodes and its child nodes. The drop event provided a rowKey for the tree node that received the drop. Like in af:table, the tree row key is not of type oracle.jbo.domain.Key but an implementation of java.util.List that contains the row keys. The JUCtrlHierBinding class in the ADF Binding layer that represents the ADF tree binding at runtime provides a method named findNodeByKeyPath that allows you to get a handle to the JUCtrlHierNodeBinding instance that represents a tree node in the binding layer. CollectionModel model = (CollectionModel) your_af_tree_reference.getValue(); JUCtrlHierBinding treeBinding = (JUCtrlHierBinding ) model.getWrappedData(); JUCtrlHierNodeBinding treeDropNode = treeBinding.findNodeByKeyPath(dropRowKey); To disclose the tree node, you need to create a RowKeySet, which you do using the RowKeySetImpl class. Because the RowKeySet replaces any existing row key set in the tree, all other nodes are automatically closed. RowKeySetImpl rksImpl = new RowKeySetImpl(); //the first key to add is the node that received the drop //operation (departments).            rksImpl.add(dropRowKey);    Similar, from the tree binding, the root node can be obtained. The root node is the end of all parent node iteration and therefore important. JUCtrlHierNodeBinding rootNode = treeBinding.getRootNodeBinding(); The following code obtains a reference to the hierarchy of parent nodes until the root node is found. JUCtrlHierNodeBinding dropNodeParent = treeDropNode.getParent(); //walk up the tree to expand all parent nodes while(dropNodeParent != null && dropNodeParent != rootNode){    //add the node's keyPath (remember its a List) to the row key set    rksImpl.add(dropNodeParent.getKeyPath());      dropNodeParent = dropNodeParent.getParent(); } Next, you disclose the drop node immediate child nodes as otherwise all you see is the department node. Its not quite exactly "dinner for one", but the procedure is very similar to the one handling the parent node keys ArrayList<JUCtrlHierNodeBinding> childList = (ArrayList<JUCtrlHierNodeBinding>) treeDropNode.getChildren();                     for(JUCtrlHierNodeBinding nb : childList){   rksImpl.add(nb.getKeyPath()); } Next, the row key set is defined as the disclosed row keys on the tree so when you refresh (PPR) the tree, the new disclosed state shows tree.setDisclosedRowKeys(rksImpl); AdfFacesContext.getCurrentInstance().addPartialTarget(tree.getParent()); The refresh in my use case is on the tree parent component (a layout container), which usually shows the best effect for refreshing the tree component. 

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• Exploring TCP throughput with DTrace

  - by user12820842

  One key measure to use when assessing TCP throughput is assessing the amount of unacknowledged data in the pipe. This is sometimes termed the Bandwidth Delay Product (BDP) (note that BDP is often used more generally as the product of the link capacity and the end-to-end delay). In DTrace terms, the amount of unacknowledged data in bytes for the connection is the different between the next sequence number to send and the lowest unacknoweldged sequence number (tcps_snxt - tcps_suna). According to the theory, when the number of unacknowledged bytes for the connection is less than the receive window of the peer, the path bandwidth is the limiting factor for throughput. In other words, if we can fill the pipe without the peer TCP complaining (by virtue of its window size reaching 0), we are purely bandwidth-limited. If the peer's receive window is too small however, the sending TCP has to wait for acknowledgements before it can send more data. In this case the round-trip time (RTT) limits throughput. In such cases the effective throughput limit is the window size divided by the RTT, e.g. if the window size is 64K and the RTT is 0.5sec, the throughput is 128K/s. So a neat way to visually determine if the receive window of clients may be too small should be to compare the distribution of BDP values for the server versus the client's advertised receive window. If the BDP distribution overlaps the send window distribution such that it is to the right (or lower down in DTrace since quantizations are displayed vertically), it indicates that the amount of unacknowledged data regularly exceeds the client's receive window, so that it is possible that the sender may have more data to send but is blocked by a zero-window on the client side. In the following example, we compare the distribution of BDP values to the receive window advertised by the receiver (10.175.96.92) for a large file download via http. # dtrace -s tcp_tput.d ^C BDP(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count -1 | 0 0 | 6 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 9 4096 | 14 8192 | 27 16384 | 67 32768 |@@ 1464 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 32396 131072 | 0 SWND(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count 16384 | 0 32768 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 17067 65536 | 0 Here we have a puzzle. We can see that the receiver's advertised window is in the 32768-65535 range, while the amount of unacknowledged data in the pipe is largely in the 65536-131071 range. What's going on here? Surely in a case like this we should see zero-window events, since the amount of data in the pipe regularly exceeds the window size of the receiver. We can see that we don't see any zero-window events since the SWND distribution displays no 0 values - it stays within the 32768-65535 range. The explanation is straightforward enough. TCP Window scaling is in operation for this connection - the Window Scale TCP option is used on connection setup to allow a connection to advertise (and have advertised to it) a window greater than 65536 bytes. In this case the scaling shift is 1, so this explains why the SWND values are clustered in the 32768-65535 range rather than the 65536-131071 range - the SWND value needs to be multiplied by two since the reciever is also scaling its window by a shift factor of 1. Here's the simple script that compares BDP and SWND distributions, fixed to take account of window scaling. #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::send / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @bdp["BDP(bytes)", args[2]-ip_daddr, args[4]-tcp_sport] = quantize(args[3]-tcps_snxt - args[3]-tcps_suna); } tcp:::receive / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @swnd["SWND(bytes)", args[2]-ip_saddr, args[4]-tcp_dport] = quantize((args[4]-tcp_window)*(1 tcps_snd_ws)); } And here's the fixed output. # dtrace -s tcp_tput_scaled.d ^C BDP(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count -1 | 0 0 | 39 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 4 4096 | 9 8192 | 22 16384 | 37 32768 |@ 99 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 3858 131072 | 0 SWND(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count 512 | 0 1024 | 1 2048 | 0 4096 | 2 8192 | 4 16384 | 7 32768 | 14 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1956 131072 | 0

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• Is UPS worthwhile for home equipment?

  - by Jon Skeet

  Over the years, I've had to throw away a quite a few bits of computing equipment (and the like): Several ADSL routers with odd symptoms (losing wireless connections, losing wired connections, DHCP failures, DNS symptoms etc) Two PVRs spontaneously rebooting and corrupting themselves (despite the best efforts of the community to diagnose and help) One external hard disk still claiming to function, but corrupting data One hard disk as part of a NAS raid array "going bad" (as far as the NAS was concerned) (This is in addition to various laptops and printers dying in ways unrelated to this question.) Obviously it'll be impossible to tell for sure from such a small amount of information, but might these be related to power issues? I don't currently have a UPS for any of this equipment. Everything on surge-protected gang sockets, but there's nothing to smooth a power cut. Is home UPS really viable and useful? I know there are some reasonably cheap UPSes on the market, but I don't know how useful they really are. I'm not interested in keeping my home network actually running during a power cut, but I'd like it to power down a bit more gracefully if the current situation is putting my hardware in jeopardy.

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• How can I make sound work without starting X?

  - by Magnus Hoff

  I have a headless machine connected to my sound system, and I am using it to run a music playing daemon that I control over the network. (Among other things) However, I can't seem to be able to have sound come out of my speakers without running X. I am running pulse audio in a system wide instance and my daemon is not running within X. Nevertheless, when my daemon is playing music without me hearing it, I can fix it by running startx in an unrelated session. After X starts, I can hear the sound. The sound disappears again if I kill the X server. Interestingly/annoyingly, the sound also stops after X has been running for a few minutes. This could possibly be because of a screen saver of some sort, but I haven't been able to verify or falsify this theory. So my current workaround is to ssh into the box whenever I want music and startx, and restart it every fifteen minutes or so. I'd like to do better. I have been able to verify the following: Adjustments in alsamixer have no effect on this problem. The relevant output channel is never muted In alsamixer, I can see no difference between when the sound is working and when it isn't Nothing is muted in pactl list There is no difference in the output from pactl list between before starting X and after it's started. (Except the identifier of the pactl instance connected to pulse, which is different each time you run pactl) The user running the music daemon is a member of the groups audio, pulse and pulse-access The music daemon program does not report any error messages and acts as if it is playing the music like it should Some form of dbus daemon is running. ps aux|grep dbus reports dbus-daemon --system --fork --activation=upstart before and after I have started X Some details about my hardware: Motherboard: http://www.asus.com/Motherboards/AT5IONTI_DELUXE/ Sound chip: Nvidia GPU 0b HDMI/DP (from alsamixer) Using HDMI for output (Machine also has an Intel Realtek ALC887 that I am not using) Output of lsmod: Module Size Used by deflate 12617 0 zlib_deflate 27139 1 deflate ctr 13201 0 twofish_generic 16635 0 twofish_x86_64_3way 25287 0 twofish_x86_64 12907 1 twofish_x86_64_3way twofish_common 20919 3 twofish_generic,twofish_x86_64_3way,twofish_x86_64 camellia 29348 0 serpent 29125 0 blowfish_generic 12530 0 blowfish_x86_64 21466 0 blowfish_common 16739 2 blowfish_generic,blowfish_x86_64 cast5 25112 0 des_generic 21415 0 xcbc 12815 0 rmd160 16744 0 bnep 18281 2 rfcomm 47604 12 sha512_generic 12796 0 crypto_null 12918 0 parport_pc 32866 0 af_key 36389 0 ppdev 17113 0 binfmt_misc 17540 1 nfsd 281980 2 ext2 73795 1 nfs 436929 1 lockd 90326 2 nfsd,nfs fscache 61529 1 nfs auth_rpcgss 53380 2 nfsd,nfs nfs_acl 12883 2 nfsd,nfs sunrpc 255224 16 nfsd,nfs,lockd,auth_rpcgss,nfs_acl btusb 18332 2 vesafb 13844 2 pl2303 17957 1 ath3k 12961 0 bluetooth 180153 24 bnep,rfcomm,btusb,ath3k snd_hda_codec_hdmi 32474 4 nvidia 11308613 0 ftdi_sio 40679 1 usbserial 47113 6 pl2303,ftdi_sio psmouse 97485 0 snd_hda_codec_realtek 224173 1 snd_hda_intel 33719 5 snd_hda_codec 127706 3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel serio_raw 13211 0 snd_seq_midi 13324 0 snd_hwdep 17764 1 snd_hda_codec snd_pcm 97275 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec snd_rawmidi 30748 1 snd_seq_midi snd_seq_midi_event 14899 1 snd_seq_midi snd_seq 61929 2 snd_seq_midi,snd_seq_midi_event snd_timer 29990 2 snd_pcm,snd_seq snd_seq_device 14540 3 snd_seq_midi,snd_rawmidi,snd_seq snd 79041 20 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device asus_atk0110 18078 0 mac_hid 13253 0 jc42 13948 0 soundcore 15091 1 snd snd_page_alloc 18529 2 snd_hda_intel,snd_pcm coretemp 13554 0 i2c_i801 17570 0 lp 17799 0 parport 46562 3 parport_pc,ppdev,lp r8169 62154 0 Any ideas? What does X do that's so important?

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• Is there a way to run CUDA applications with the CUDA device being a secondary adapter?

  - by Slartibartfast

  I've been trying to run a CUDA program on a remote computer which has Windows 7 installed. The GPU is GeForce GTX 480. One of the problems I've been facing is that, the computer has two adapters, 1) Standard VGA Adapter 2) NVIDIA GeForce GTX 480 Even though this shows in the device manager. The desktop uses the standard VGA Adapter. I'm assuming this is because the Standard VGA is the primary adapter. Also the device manager shows that the monitor is connected to the standard VGA Adapter. In this scenario if i try to run any CUDA application it fails to recognise a CUDA capable device. Is it necessary for the NVIDIA adapter to be the primary one? Or is there any way to use CUDA when the graphics card is a secondary adapter. I've seen a few posts in the NVIDIA forums on this before, one suggests using another low cost NVIDIA card as the primary adapter, but that is currently not an option. I couldn't find any other solutions. Thanks I tried running the deviceQuery test from the NVIDIA GPU Computing Samples. This was the result i obtained CUDA Device Query (Runtime API) version (CUDART static linking) cudaGetDeviceCount FAILED CUDA Driver and Runtime version may be mismatched FAILED The driver version I'm using is 263.06. The CUDA version is 3.2 I ran the same test on my desktop which also has windows 7 and a GeForce GTX 465. The CUDA toolkit version is 3.2. The driver version was the same and the test passed, although it failed with an older driver.

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• What is a long-term strategy to deal with CPU fan dust in my home office?

  - by PaulG

  There are numerous discussions of CPU overheating and how sometimes this can be corrected by removing the dust from the CPU fan. I have read many of these, but I can't find anyone expressing a long-term strategy to deal with this problem. There are some suggestions here, for example, about how often the inside of the computer should be dusted. But I find this generally unsatisfactory. As it stands, in my rather dusty house (heated by a wood stove, with no central air circulation), I need to vacuum out the CPU fan every 3 to 4 months. At high CPU load, this can make a difference between 65C and 100C. I'm tired of hauling out the vacuum every time I anticipate high CPU load. What steps can I take to deal with this systematically in the long-term? Moving my high CPU load computing to the cloud is not a realistic option. Neither is vacuuming my home office more than once a week! (Details: my computer is on the floor in a Cooler Master HAF922 case, and uses an Intel CPU fan on an i7 chip) EDIT: While this would definitely solve the problem (submerging motherboard in mineral oil), it is a bit of an expensive solution.

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• Going by the eBook

  - by Tony Davis

  The book and magazine publishing world is rapidly going digital, and the industry is faced with making drastic changes to their ways of doing business. The sudden take-up of digital readers by the book-buying public has surprised even the most technological-savvy of the industry. Printed books just aren't selling like they did. In contrast, eBooks are doing well. The ePub file format is the standard around which all publishers are converging. ePub is a standard for formatting book content, so that it can be reflowed for various devices, with their widely differing screen-sizes, and can be read offline. If you unzip an ePub file, you'll find familiar formats such as XML, XHTML and CSS. This is both a blessing and a curse. Whilst it is good to be able to use familiar technologies that have been developed to a level of considerable sophistication, it doesn't get us all the way to producing a viable publication. XHTML is a page-description language, not a book-description language, as we soon found out during our initial experiments, when trying to specify headers, footers, indexes and chaptering. As a result, it is difficult to predict how any particular eBook application will decide to render a book. There isn't even a consensus as to how the cover image is specified. All of this is awkward for the publisher. Each book must be created and revised in a form from which can be generated a whole range of 'printed media', from print books, to Mobi for kindles, ePub for most Tablets and SmartPhones, HTML for excerpted chapters on websites, and a plethora of other formats for other eBook readers, each with its own idiosyncrasies. In theory, if we can get our content into a clean, semantic XML form, such as DOCBOOKS, we can, from there, after every revision, perform a series of relatively simple XSLT transformations to output anything from a HTML article, to an ePub file for reading on an iPad, to an ICML file (an XML-based file format supported by the InDesign tool), ready for print publication. As always, however, the task looks bigger the closer you get to the detail. On the way to the utopian world of an XML-based book format that encompasses all the diverse requirements of the different publication media, ePub looks like a reasonable format to adopt. Its forthcoming support for HTML 5 and CSS 3, with ePub 3.0, means that features, such as widow-and-orphan controls, multi-column flow and multi-media graphics can be incorporated into eBooks. This starts to make it possible to build an "app-like" experience into the eBook and to free publishers to think of putting context before container; to think of what content is required, be it graphical, textual or audio, from the point of view of the user, rather than what's possible in a given, traditional book "Container". In the meantime, there is a gap between what publishers require and what current technology can provide and, of course building this app-like experience is far from plain sailing. Real portability between devices is still a big challenge, and achieving the sort of wizardry seen in the likes of Theodore Grey's "Elements" eBook will require some serious device-specific programming skills. Cheers, Tony.

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• Problems with moving 2D circle/box collision detection

  - by dario3004

  This is my first game ever and I'm a newbie in computer physics. I've got this code for the collision detection and it works fine for BOTTOM and TOP collision.It miss the collision detection with the paddle's edge and angles so I've (roughly) tried to implement it. Main method that is called for bouncing, it checks if it bounce with wall, or with top (+ right/left side) or with bottom (+ right/left side): protected void handleBounces(float px, float py) { handleWallBounce(px, py); if(mBall.y < getHeight()/4){ if (handleRedFastBounce(mRed, px, py)) return; if (handleRightSideBounce(mRed,px,py)) return; if (handleLeftSideBounce(mRed,px,py)) return; } if(mBall.y > getHeight()/4 * 3){ if (handleBlueFastBounce(mBlue, px, py)) return; if (handleRightSideBounce(mBlue,px,py)) return; if (handleLeftSideBounce(mBlue,px,py)) return; } } This is the code for the BOTTOM bounce: protected boolean handleRedFastBounce(Paddle paddle, float px, float py) { if (mBall.goingUp() == false) return false; // next position tx = mBall.x; ty = mBall.y - mBall.getRadius(); // actual position ptx = px; pty = py - mBall.getRadius(); dyp = ty - paddle.getBottom(); xc = tx + (tx - ptx) * dyp / (ty - pty); if ((ty < paddle.getBottom() && pty > paddle.getBottom() && xc > paddle.getLeft() && xc < paddle.getRight())) { mBall.x = xc; mBall.y = paddle.getBottom() + mBall.getRadius(); mBall.bouncePaddle(paddle); playSound(mPaddleSFX); increaseDifficulty(); return true; } else return false; } As long as I understood it should be something like this: So I tried to make the "left side" and "right side" bounce method: protected boolean handleLeftSideBounce(Paddle paddle, float px, float py){ // next position tx = mBall.x + mBall.getRadius(); ty = mBall.y; // actual position ptx = px + mBall.getRadius(); pty = py; dyp = tx - paddle.getLeft(); yc = ty + (pty - ty) * dyp / (ptx - tx); if (ptx < paddle.getLeft() && tx > paddle.getLeft()){ System.out.println("left side bounce1"); System.out.println("yc: " + yc + "top: " + paddle.getTop() + " bottom: " + paddle.getBottom()); if (yc > paddle.getTop() && yc < paddle.getBottom()){ System.out.println("left side bounce2"); mBall.y = yc; mBall.x = paddle.getLeft() - mBall.getRadius(); mBall.bouncePaddle(paddle); playSound(mPaddleSFX); increaseDifficulty(); return true; } } return false; } I think I'm quite near to the solution but I'm having big troubles with the new "yc" formula. I tried so many versions of it but since I don't know the theory behind it I can't adjust for the Y axis. Since the Y axis is inverted I even tried this: yc = ty - (pty - ty) * dyp / (ptx - tx); I tried Googling it but I can't seem to find a solution for it. Also this method fails when ball touches the angle and I don't think is a nice way because it just test "one" point of the ball and probably there will be many cases in which the ball won't bounce.

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• How to share text, pictures and video to restricted set of users

  - by joaoc

  I want to share pictures and videos of my kid growing up but I don't want it to be open to the public. I just want me and my wife to be able to add material and then share with grandparents and friends who would be given a username/password or some other solution that authenticates them. This content would preferably be available remotely over the internet or downloaded periodically to the allowed viewers computers. The second option most likely means they would have to install a client, which I am not too fond of doing (I would have to ask them to install it, help configure for different platforms, ...) I'm at the start but I would like software that also allows export of the data (if one day I want to migrate to a different solution). Folder sharing I don't know if Windows folder sharing is reliable, robust and safe enough to share over the internet. Dropbox could be a software solution, but it's limited to 2GB and requires receivers to also install and configure software. A folder is just a collection of files, so it would be harder to keep them organized with text describing the pictures/video Email I could email the content every now and then but videos are almost always too big to go as attachments This would also not provide a history of updates to anyone just recently joining in Are there other solutions to achieve this? NOTE: I also thought that software to run a local or remote blog could be an option but we aren't allowed to ask those questions on superuser because one admin doesn't like cloud-computing questions. But if you do think it's the best approach and can suggest a solution, do state it in the answers anyway!

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• Learn Many Languages

  - by Jeff Foster

  My previous blog, Deliberate Practice, discussed the need for developers to “sharpen their pencil” continually, by setting aside time to learn how to tackle problems in different ways. However, the Sapir-Whorf hypothesis, a contested and somewhat-controversial concept from language theory, seems to hold reasonably true when applied to programming languages. It states that: “The structure of a language affects the ways in which its speakers conceptualize their world.” If you’re constrained by a single programming language, the one that dominates your day job, then you only have the tools of that language at your disposal to think about and solve a problem. For example, if you’ve only ever worked with Java, you would never think of passing a function to a method. A good developer needs to learn many languages. You may never deploy them in production, you may never ship code with them, but by learning a new language, you’ll have new ideas that will transfer to your current “day-job” language. With the abundant choices in programming languages, how does one choose which to learn? Alan Perlis sums it up best. “A language that doesn‘t affect the way you think about programming is not worth knowing“ With that in mind, here’s a selection of languages that I think are worth learning and that have certainly changed the way I think about tackling programming problems. Clojure Clojure is a Lisp-based language running on the Java Virtual Machine. The unique property of Lisp is homoiconicity, which means that a Lisp program is a Lisp data structure, and vice-versa. Since we can treat Lisp programs as Lisp data structures, we can write our code generation in the same style as our code. This gives Lisp a uniquely powerful macro system, and makes it ideal for implementing domain specific languages. Clojure also makes software transactional memory a first-class citizen, giving us a new approach to concurrency and dealing with the problems of shared state. Haskell Haskell is a strongly typed, functional programming language. Haskell’s type system is far richer than C# or Java, and allows us to push more of our application logic to compile-time safety. If it compiles, it usually works! Haskell is also a lazy language – we can work with infinite data structures. For example, in a board game we can generate the complete game tree, even if there are billions of possibilities, because the values are computed only as they are needed. Erlang Erlang is a functional language with a strong emphasis on reliability. Erlang’s approach to concurrency uses message passing instead of shared variables, with strong support from both the language itself and the virtual machine. Processes are extremely lightweight, and garbage collection doesn’t require all processes to be paused at the same time, making it feasible for a single program to use millions of processes at once, all without the mental overhead of managing shared state. The Benefits of Multilingualism By studying new languages, even if you won’t ever get the chance to use them in production, you will find yourself open to new ideas and ways of coding in your main language. For example, studying Haskell has taught me that you can do so much more with types and has changed my programming style in C#. A type represents some state a program should have, and a type should not be able to represent an invalid state. I often find myself refactoring methods like this… void SomeMethod(bool doThis, bool doThat) { if (!(doThis ^ doThat)) throw new ArgumentException(“At least one arg should be true”); if (doThis) DoThis(); if (doThat) DoThat(); } …into a type-based solution, like this: enum Action { DoThis, DoThat, Both }; void SomeMethod(Action action) { if (action == Action.DoThis || action == Action.Both) DoThis(); if (action == Action.DoThat || action == Action.Both) DoThat(); } At this point, I’ve removed the runtime exception in favor of a compile-time check. This is a trivial example, but is just one of many ideas that I’ve taken from one language and implemented in another.

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• Building vs buying a server for an academic lab [closed]

  - by Roy

  I'm looking for advice on the classic build vs buy question. We need a new linux server to run Matlab computation on in our lab (academic). Matlab parallel computing toolbox licence allows up to 12 local workers so we are aiming at a 12 core server with 4GB memory per core (total of 48gb). The system will have an SSD for the OS and a raid-5 (4x2tb) for data. I looked around and found a (relatively) cheap vendor, Silicon Mechanics, that offers a system to our liking (specs below) for $6732. However, buying the components from newegg cost only $4464! The difference is $2268 which is 50% of the base cost. If buying from a company can be thought of as a sort of insurance, basically my premiums are of 50% of the base cost which to me sounds like a lot. Of course any downtime is bad, but the work is not "mission critical", i.e. if it takes a few days to fix it when it breaks its no the end of the world. If it takes weeks to months then its a problem. If it breaks 2-3 times in 3 years, not too bad. If it breaks every month not good. In term of build experience, I set up a linux cluster in grad school (from existing computers) and I build my home pcs but I never built a server before. The server components I'm thinking about: 1 x SUPERMICRO SYS-7046T-6F 4U Tower Server Barebone Dual LGA 1366 Intel 5520 DDR3 1333/1066/800 ($1,050) 12 x Kingston 4GB 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10600) ECC Unbuffered Server Memory ($420) 2 x Intel Xeon E5645 Westmere-EP 2.4GHz LGA 1366 80W Six-Core ($1,116) 4 x Seagate Constellation ES 2TB 7200 RPM SATA 6.0Gb/s 3.5" ($1,040) 1 x SAMSUNG Internal DVD Writer Black SATA ($20) 1 x Intel 520 Series 2.5" 180GB SATA III MLC SSD $300 1 x LSI LSI00281 PCI-Express 2.0 x8 MD2 Low profile SATA / SAS MegaRAID SAS 9260CV-4i Controller Card, $695

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• PowerShell and SMO – be careful how you iterate

  - by Fatherjack

  I’ve yet to have a totally smooth experience with PowerShell and it was late on Friday when I crashed into this problem. I haven’t investigated if this is a generally well understood circumstance and if it is then I apologise for repeating everything. Scenario: I wanted to scan a number of server for many properties, including existing logins and to identify which accounts are bestowed with sysadmin privileges. A great task to pass to PowerShell, so with a heavy heart I started up PowerShellISE and started typing. The script doesn’t come easily to me but I follow the logic of SMO and the properties and methods available with the language so it seemed something I should be able to master. Version #1 of my script. And the results it returns when executed against my home laptop server. These results looked good and for a long time I was concerned with other parts of the script, for all intents and purposes quite happy that this was an accurate assessment of the server. Let’s just review my logic for each step of the code at the top. Lines 1 to 7 just set up our variables and write out the header message Line 8 our first loop, to go through each login on the server Line 10 an inner loop that will assess each role name that each login has been assigned Line 11 a test to see if each role has the name ‘sysadmin’ Line 13 write out the login name with a bright format as it is a sysadmin login Line 17 write out the login name with no formatting It is quite possible that here someone with more PowerShell experience than me will be shouting at their screen pointing at the error I made but to me this made total sense. Until I altered the code, I altered lines 6 and 7 of code above to be: $c = $Svr.Logins.Count write-host “There are $c Logins on the server” This changed my output to look like this: This started alarm bells ringing – there are clearly not 13 logins listed So, let’s see where things are going wrong, edit the script so it looks like this. I’ve highlighted the changes to make Running this code shows me these results Our $n variable should count up by one for each login returned and We are clearly missing some logins. I referenced this list back to Management Studio for my server and see the Logins as below, where there are clearly 13 logins. We see a Login called Annette in SSMS but not in the script results so I opened that up and looked at its properties and it’s server roles in particular. The account has only public access to the server. Inspection of the other logins that the PowerShell script misses out show they too are only members of the public role. Right now I can’t work out whether there is a good reason for this and if it should be expected behaviour or not. Please spend a few minutes to leave a comment if you have an opinion or theory for this. How to get the full list of logins. Clearly I needed to get a full list of the logins so set about reviewing my code to see if there was a better way to iterate through the roles for each login. This is the code that I came up with and I think it is doing everything that I need it to. It gives me the expected results like this: So it seems that the ListMembers() method is the trouble maker in my first versions of the code. I would have expected that ListMembers should return Logins that are only members of the public role, certainly Technet makes no reference to it being left out in it’s Login.ListMembers details. Suffice to say, it’s a lesson learned and I will approach using it with caution in future circumstances.

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• Blind As a Bat in Multi-Monitor Hell &ndash; Free Program Inside!

  - by ToStringTheory

  If you know me personally, then you probably know that I am going blind thanks to a rare genetic eye disease.  My eye disease has already been a huge detriment to my eyesight.  One of the big things to suffer is my ability to see small things moving fast right in front of me.  On a multi-monitor setup, this makes finding the cursor absolute hell. The Problem I’ll keep this short, as I’ve basically already told you what the problem is.  On my three monitor development computer, I am constantly losing the mouse during the day.  I had used the Microsoft accessibility mousefinder (press CTRL, and it pings around the mouse).  The problem with this is, there is only an effect around 50-100 PX around the mouse, and it is a very light gray, almost unnoticeable.. For someone like me, if I am not looking at the monitor when I click the CTRL button, I have to click it multiple times and dart my eyes back and forth in a futile attempt to catch a glimpse of the action…  I had tried other cursor finders, but none I liked… The Solution So what’s a guy to do when he doesn’t like his options?  MAKE A NEW OPTION…  What else should we as developers do, am I right?  So, I went ahead and made a mousefinder of my own, with 6 separate settings to change the effect.  I am releasing it here for anyone else that may also have problems finding their mouse at times. Some of its features include: Multiple options to change to achieve the exact effect you want. If your mouse moves while it is honing in, it will hone in on its current position. Many times, I would press the button and move my mouse at the same time, and many times, the mouse happened to be at a screen edge, so I would miss it. This program will restart its animation on a new screen if the mouse changes its screen while playing. Tested on Windows 7 x64 Stylish color changing from green to red. Deployed as a ClickOnce, so easy to remove if you don't like it. Press Right CTRL to trigger effect Application lives in notification area so that you can easily reach configuration or close it. To get it to run on startup, copy its application shortcut from its startmenu directory to the “Startup” folder in your startmenu. Conclusion I understand if you don’t download this…  You don’t know me and I don’t know you.  I can only say that I have honestly NOT added any virus’ or malware to the package. Yeah, I know it’s weird Download: ‘ToString(theory) Mousefinder.zip’ CRC32: EEBCE300 MD5: 0394DA581BE6F3371B5BA11A8B24BC91 SHA-1: 2080C4930A2E7D98B81787BB5E19BB24E118991C Finally, if you do use this application - please leave a comment, or email me and tell me what you think of it. Encounter a bug or hashes no longer match? I want to know that too! <warning type=”BadPun”>Now, stop messing around and start mousing around!</warning>

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• Printer Naming Conventions

  - by John

  I am working on building a new AD print server and have been pondering the idea of renaming the printers. Right now we have a mix of names that varies between a mashup of some that reference location, some that reference functional area, and some that are rather generic. Some examples include the following: Dell 5210 - Building Name HP 4350 - Functional Area Dell Color 3100 - Location and Building Number HP 6500 - Mailroom I was curious what other people used to name their printers with. What conventions do you use and how to design a method that will be able to be used for a while without needing to rename them all again. Also, the naming methodology needs to be understandable for regular computing users so that they can relatively easily find the printer that they need. I was looking at some ideas from here, but I was not sure how practical some of them are. Any help that you can provide is appreciated. Note: I have reviewed many of the postings on here in relation to server naming conventions and found that they were not specific enough for the use case I present above.

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• What Counts For a DBA – Depth

  - by Louis Davidson

  SQL Server offers very simple interfaces to many of its features. Most people could open up SSMS, connect to a server, write a simple query and see the results. Even several of the core DBA tasks are deceptively straightforward. It doesn’t take a rocket scientist to perform a basic database backup or run a trace (even using the newfangled Extended Events!). However, appearances can be deceptive, and often times it is really important that a DBA understands not just the basics of how to perform a task, but why we do a task, and how that task works. As an analogy, consider a child walking into a darkened room. Most would know that they need to turn on the light, and how to do it, so they flick the switch. But what happens if light fails to shine forth. Most would immediately tell you that you need to consider changing the light bulb. So you hop in the car and take them to the local home store and instruct them to buy a replacement. Confronted with a 40 foot display of light bulbs, how will they decide which of the hundreds of types of bulbs, of different types, fittings, shapes, colors, power and efficiency ratings, is the right choice? Obviously the main lesson the child is going to learn this day is how to use their cell phone as a flashlight so they don’t have to ask for help the next time. Likewise, when the metaphorical toddlers who use your database server have issues, they will instinctively know something is wrong, and may even have some idea what caused it, but will have no depth of knowledge to figure out the right solution. That is where the DBA comes in and attempts to save the day. However, when one looks beneath the shiny UI, SQL Server has its own “40 foot display of light bulbs”, in the form of the tremendous number of tools and the often-bewildering amount of information they can present to the DBA, to help us find issues. Unfortunately, resorting to guesswork, to trying different “bulbs” over and over, hoping to stumble on the answer. This is where the right depth of knowledge goes a long way. If we need to write a SELECT statement, then knowing the syntax and where to find the data is not enough. Knowledge of indexes and query plans is essential. Without it, we might hit on a query that “works”, but we are basically still a user, not a programmer, because we have no real control over our platform. Is that level of knowledge deep enough? Probably not, since knowledge of the underlying metadata and structures would be very useful in helping us make sense of any query plan. Understanding the structure of an index makes the “key lookup” operator not sound like what you do when someone tapes your car key to the ceiling. So is even this level of understanding deep enough? Do we need to understand the memory architecture used to process the query? It might be a comforting level of knowledge, and will doubtless come in handy at some point, but is not strictly necessary in most cases. Beyond that lies (more or less) full knowledge of SQL language and the intricacies of every step the SQL Server engine takes to process our query. My personal theory is that, as a professional, our knowledge of a given task should extend, at a minimum, one level deeper than is strictly necessary to perform the task. Anything deeper can be left to the ridiculously smart, or obsessive, or both. As an example. tasked with storing an integer value between 0 and 99999999, it’s essential that I know that choosing an Integer over Decimal(8,0) will likely offer performance benefits. It is then useful that I also understand the value of adding a CHECK constraint, to make sure the values are valid to the desired range; and comforting that I know a little about the underlying processors, registers and computer math. Anything further, I leave to the likes of Joe Chang, whose recent blog post on the topic offers depth by the bucketful!  

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• KVM Hosting: How to efficiently replicate guests

  - by javano

  I have three KVM servers each with 1 guest VM, running directly on it's local storage, (so they are essentially getting a dedicated box worth of computing power each). In the event of a host failure I would like the guests replicated to at least one of the other hosts so I can spin it up there, until the failing host is fixed. I am curious about KVM cloning. I can clone a VM live or when it's suspended/shutdown. Obivously suspended VMs will naturally be quicker to clone but these three VMs comprise three parts of a single solution, so I don't want to ever have any one of them shutdown. How can I efficiently clone these VMs between servers? I have had a couple of ideas, but are these insane or, is there a better method I have missed for my scenario? Set up a DRDB partition between box 1 and 2 where VM 1 runs from, and so is replicated between box1 and box 2, repeat between box 2 & 3, and box 3 & 1 (This could be insane, I have never used DRDB only read about it) Just use standard KVM CLI clone options to perform live clones (I'm dubious about this because I don't know how long it will take and what the performance impact will be during) Run a copy of each VM on at least one other host, and have the guest on one host export it's data to the matching guest on another host where it can import that data, scripting this on the guest) Some of other way? Ideas welcome! Side Note These servers have 4x15k SAS drives in a RAID 10 so they aren't rocketing fast, and as I mentioned, each VM runs from the host's local storage, no NAS or SAN etc. So that is why I am asking this question about guest replication. Also, this isn't about disaster recovery. Guests will be exporting their data to a NAS over a VPN, so I am looking at how I can have them quickly spun up in a host failure situation.

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• What Counts for a DBA: Skill

  - by drsql

  “Practice makes perfect:” right? Well, not exactly. The reality of it all is that this saying is an untrustworthy aphorism. I discovered this in my “younger” days when I was a passionate tennis player, practicing and playing 20+ hours a week. No matter what my passion level was, without some serious coaching (and perhaps a change in dietary habits), my skill level was never going to rise to a level where I could make any money at the sport that involved something other than selling tennis balls at a sporting goods store. My game may have improved with all that practice but I had too many bad practices to overcome. Practice by itself merely reinforces what we know and what we can figure out naturally. The truth is actually closer to the expression used by Vince Lombardi: “Perfect practice makes perfect.” So how do you get to become skilled as a DBA if practice alone isn’t sufficient? Hit the Internet and start searching for SQL training and you can find 100 different sites. There are also hundreds of blogs, magazines, books, conferences both onsite and virtual. But then how do you know who is good? Unfortunately often the worst guide can be to find out the experience level of the writer. Some of the best DBAs are frighteningly young, and some got their start back when databases were stored on stacks of paper with little holes in it. As a programmer, is it really so hard to understand normalization? Set based theory? Query optimization? Indexing and performance tuning? The biggest barrier often is previous knowledge, particularly programming skills cultivated before you get started with SQL. In the world of technology, it is pretty rare that a fresh programmer will gravitate to database programming. Database programming is very unsexy work, because without a UI all you have are a bunch of text strings that you could never impress anyone with. Newbies spend most of their time building UIs or apps with procedural code in C# or VB scoring obvious interesting wins. Making matters worse is that SQL programming requires mastery of a much different toolset than most any mainstream programming skill. Instead of controlling everything yourself, most of the really difficult work is done by the internals of the engine (written by other non-relational programmers…we just can’t get away from them.) So is there a golden road to achieving a high skill level? Sadly, with tennis, I am pretty sure I’ll never discover it. However, with programming it seems to boil down to practice in applying the appropriate techniques for whatever type of programming you are doing. Can a C# programmer build a great database? As long as they don’t treat SQL like C#, absolutely. Same goes for a DBA writing C# code. None of this stuff is rocket science, as long as you learn to understand that different types of programming require different skill sets and you as a programmer must recognize the difference between one of the procedural languages and SQL and treat them differently. Skill comes from practicing doing things the right way and making “right” a habit.

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