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• Deactivate SYN flooding mechanism

  - by mlaug

  I am running a server that is running a service on port 59380. There are more than 1000 machines out there connecting to that service. Once I need to restart the service all those machines are connecting at the same time. That made some trouble as I have seen that log entry in kern.log TCP: Possible SYN flooding on port 59380. *Sending cookies*. Check SNMP counters. So I changed sysctl net.ipv4.tcp_syncookies to 0 because the endpoints to not handle tcp syn cookies correctly. Finally I restarted my network to get the changes in production Next time I had to restart the service, the following message was logged TCP: Possible SYN flooding on port 59380. *Dropping request*. Check SNMP counters. How can I prevent the system for doing such actions? All necessary counter measures are done by iptables...

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• Debian Based Server not booting, soon after GRUB screen it restarts?

  - by Krauser

  I have tried running memtest, it start get about half way then abruptly restarts. I assume this is not a problem with the OS itself but rather a hardware issue, I have checked various logs when after about 10 reboots it starts ok, /var/log/kern.log /var/log/syslog /var/log/dmesg All I get is: EXT4-fs(sdc1): re-mounted. Opts: errors=remount-ro restart So I ran fcsk on the drive, to check if the fs was failing and it was fine. Really don't know how to find why the server is continuosly restarting andif I get lucky it will boot up.

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• Unable to suspend with FGLRX enabled

  - by schmmd

  I am unable to suspend in a fully updated (as of yesterday, 29 March 2011) Ubuntu 10.10 installation (kernel 2.6.35-28). Following is a list of some of my hardware: Motherboard: Gigabyte GA-X58A-UD3R Video: Radeon HD-567X-YNF3 Initially, when I went to either Suspend or Hibernate the machine would almost go into suspend, but it would never power down. Instead it would bounce back to the login screen. This was due to a problem with the USB3 ports being unable to suspend (noticed this in /var/log/kern.log). Disabling the USB3 ports in the BIOS fixed this issue. Now Suspend and Hibernate power down the machine. It successfully awakens from Hibernate. However, it will not return from suspend. The mouse and keyboard are not powered and the monitor has no signal. These devices are still not powered after a restart. I must power-cycle the machine. The pm-suspend log ends after it states that it entered suspend (i.e. there is no information any resume code running). I discovered that acpitool -s suspends the machine and resumes successfully exactly once. The second time the machine will not resume. I am not sure how these two tools handle suspend differently. UPDATE: the problem was introduced somewhere between 2.6.35-22 and 2.6.35-28. I have both kernels install presently. Suspend works fine with 2.6.35-22 but not with 2.6.38-28.

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• DSL PPPoE connection not working?

  - by Mussnoon

  I use a wired PPPoE connection to connect to the Internet. What I need to do on Windows to connect to it is put in static IP address, gateway, subnet mask and DNS servers for my LAN card. Next I have to create a dialer for a PPPoE connection, put in my user name, the service name and the password, and "dial" this connection. And it works fine. On Ubuntu 10.04, however, I have tried setting things up in a similar fashion - put in all static addresses for the "automatic" wired connection, then put in user name, service name, password for a "DSL" connection. It worked for a while, then stopped. I have tried putting in all the details within the DSL configuration dialog, same thing happened - it worked for a while, then stopped. I have tried deleting the ethernet connection and only keeping the DSL one with all the numbers put in place, same thing happened - it worked for a while, then stopped. Each of the times, when it connected, it connected randomly, after trying a few times, and either stopped working within a few minutes, or after I had rebooted. I have deleted and remade the connection dozens of times - even with different names, but nothing seems to be working. I have also tried pppoeconf from the terminal, didn't work. I have checked /var/log/kern.log, but nothing changes in the file when I try to connect. I have also checked /sbin/route, but gedit can't even open it (says it can't figure the character encoding...). The "connection established" notification pops up from the top right corner, the same way as when the computer is actually connected to a network. Can anyone figure what's wrong and how it can be solved?

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• DSL connection not working in 10.04

  - by Mussnoon

  I use a wired PPPoE connection to connect to the Internet. What I need to do on Windows to connect to it is put in static IP address, gateway, subnet mask and DNS servers for my LAN card. Next I have to create a dialer for a PPPoE connection, put in my user name, the service name and the password, and "dial" this connection. And it works fine. On Ubuntu 10.04, however, I have tried setting things up in a similar fashion - put in all static addresses for the "automatic" wired connection, then put in user name, service name, password for a "DSL" connection. It worked for a while, then stopped. I have tried putting in all the details within the DSL configuration dialog, same thing happened - it worked for a while, then stopped. I have tried deleting the ethernet connection and only keeping the DSL one with all the numbers put in place, same thing happened - it worked for a while, then stopped. Each of the times, when it connected, it connected randomly, after trying a few times, and either stopped working within a few minutes, or after I had rebooted. I have deleted and remade the connection dozens of times - even with different names, but nothing seems to be working. I have also tried pppoeconf from the terminal, didn't work. I have checked /var/log/kern.log, but nothing changes in the file when I try to connect. I have also checked /sbin/route, but gedit can't even open it (says it can't figure the character encoding...). The "connection established" notification pops up from the top right corner, the same way as when the computer is actually connected to a network. Can anyone figure what's wrong and how it can be solved?

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• check what process was causing the problem of high cpu load

  - by linuxk

  I'm running nginx wordpress server in KVM using 12.04 server x86. It was running very well about 4 month until 2 hours ago. I found that my website is down and no ping response. Virt-manager logged high cpu load(plz see the picture below) before unexpected shut down. I want to know what process caused unexpected shutdown. The following log files make me think my server is attacked. Any suggestions and help would be appreciated. kern.log and syslog showed me same output. Nov 11 03:54:11 www kernel: [1344541.156239] [UFW BLOCK] IN=eth0 OUT= MAC= SRC=0.0.0.0 DST=224.0. 0.1 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2 Nov 11 03:54:11 www kernel: [1344541.156315] [UFW BLOCK] IN=eth0 OUT= MAC= SRC=0101:080a:2334:c90 0:0100:0000:0000:0000 DST=ff02:0000:0000:0000:0000:0000:0000:0001 LEN=72 TC=0 HOPLIMIT=1 FLOWLBL=0 PROTO=ICMPv6 TYPE=130 CODE=0 /nginx/access.log showed me 119.235.237.17 - - [11/Nov/2012:03:45:29 +0900] "GET /blog HTTP/1.1" 200 30493 "-" "Yeti/1.0 (NHN Corp.; http://help.naver.com/robots/)" my-server-ip - - [11/Nov/2012:11:05:30 +0900] "POST /wp-cron.php?doing_wp_cron=13 HTTP/1.0" 499 0 "-" "WordPress/3.4.2; http://mywebsite.com" Server turned on in here. 119.235.237.16 - - [11/Nov/2012:11:05:30 +0900] "GET /blog HTTP/1.1" 200 32935 "-" "Yeti/1.0 (NHN Corp.; http://help.naver.com/robots/)"

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• Bad DMA/do_IRQ errors on suspend/resume, with occasional freezing

  - by Steve Kroon

  Every time I suspend or resume my laptop (Dell Latitude E6520, bought this year), I get 2 messages of the form displayed on the console just before shutting down/starting up: [ 407.107610] ehci_hcd 0000:00:1d.0: dma_pool_free buffer-128, f6f18000/36f18000 (bad dma) On occasion, I get a message of the form: [ 3753.979066] do_IRQ: 0.177 No irq handler for vector (irq -1) On occasion, my machine freezes with a flashing Caps Lock button when suspending, after which I need to do a hard shutdown. This never happened before the messages started appearing (a while back), and I think it never happens without a do_IRQ message appearing (although I'm not sure about that). [There's nothing in the owner's manual on a flashing Caps Lock button; apparently it may be a kernel panic if the scroll lock also flashes, but the laptop doesn't have a scroll lock light, and there's no message on the console saying kernel panic.] Are these bad DMA/do IRQ messages serious, and what can I do to investigate/troubleshoot them and the freezing? Edit: I've also now received the following error messages a few times: [246943.023908] JBD: I/O error detected when updating journal superblock for sdb1. [246943.023958] Buffer I/O error on device sdb1, logical block 0 [246943.023996] EXT3-fs (sdb1): I/O error while writing superblock Edit: Output of dmesg at http://pastebin.com/ra7MTQEj ; contents of /var/log/kern.log at http://pastebin.com/i6jf0Md9 Edit: the output of some smartctl (-a, -x, --log=error, --log=xerror) instructions is available at http://paste.ubuntu.com/1088488/ . Edit (31/8/2012): Output of dmesg|grep -i ehci available at http://paste.ubuntu.com/1177246/ .

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• CIFS shares do not mount after upgrade to 12.10 from 12.04

  - by Mothball

  I have seen issues close to my problem but no one seems to have a definitive answer as to what is going on and why the failure occurs. I have a number of NAS devices on my home network and on a previous install of 12.04 and version prior mounting at login worked using this entry for each in fstab: //servername/sharename /media/windowsshare cifs guest,uid=1000,iocharset=utf8,codepage=cp850,cp850 0 0 Now when I use this, 12.10 reports the standard - cannot mount bad option ... blah blah... The kern log reports that the CIFS option "codepage" unknown... changed entry to "unicode" and received the same error message. There are no other error messages or log entries that would indicate another issue, but this is the statement I used for quite awhile with version 12.04 and before. Is the codepage option obsolete in 12.10/CIFS now? Is there a codepage support program that I must load? Is there some kind of helper program that is required to supports the codepage option? A current review of the man pages at samba.org does not make mention of the option "codepage". Extremely confused - any help/insight would be greatly appreciated.

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• How to diagnose Ubuntu CPU spikes / IO wait?

  - by Jeff Welling

  I'm using Ubuntu and every couple minutes it goes unresponsive for a half second to a full second, which isn't normally a problem but makes trying to code extremely frustrating when your trying to hit backspace or navigate the code and nothing is happening. The problem is, the freezes are so brief that top doesn't have time to show me what is spiking the CPU (assuming something is, but I don't know what else could cause this). Does anyone know how to troubleshoot this performance issue? Edit: I've tried login in with Gnome Classic (No Effects) instead of Unity but it still freezes up every once in awhile. Edit: The CPU graph doesn't seem to be showing any actual spikes so it seems you were right and my original diagnosis of CPU spikes being the problem was incorrect, I now suspect IO wait. I don't recall this happening for the brief few weeks I had Windows 7 Starter running on it though, which leads me to believe it isn't (just?) the hardware.. is there anything I can tweak to improve this? I'm using an Acer Aspire One D257, with Ubuntu 11.10. Edit: Output of dmesg is at http://paste.ubuntu.com/1060054/ and kern.log is at http://paste.ubuntu.com/1060055/

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• Very large log files, what should I do?

  - by Masroor

  (This question deals with a similar issue, but it talks about a rotated log file.) Today I got a system message regarding very low /var space. As usual I executed the commands in the line of sudo apt-get clean which improved the scenario only slightly. Then I deleted the rotated log files which again provided very little improvement. Upon examination I find that some log files in the /var/log has grown up to be very huge ones. To be specific, ls -lSh /var/log gives, total 28G -rw-r----- 1 syslog adm 14G Aug 23 21:56 kern.log -rw-r----- 1 syslog adm 14G Aug 23 21:56 syslog -rw-rw-r-- 1 root utmp 390K Aug 23 21:47 wtmp -rw-r--r-- 1 root root 287K Aug 23 21:42 dpkg.log -rw-rw-r-- 1 root utmp 287K Aug 23 20:43 lastlog As we can see, the first two are the offending ones. I am mildly surprised why such large files have not been rotated. So, what should I do? Simply delete these files and then reboot? Or go for some more prudent steps? I am using Ubuntu 14.04.

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• How do I debug xorg/fglrx related system freezes on Ubuntu 12.10?

  - by racerror

  My brand new system is randomly freezing and I don't know how to debug the issue. System: AMD A10-5800k Asus F2A85-M motherboard Integrated Radeon HD 7660D 8gb Samsung ddr3 1600 Ubuntu 12.10 Gnome shell / Unity (issue exists in both) xorg.conf (relevant parts): Section "Device" Identifier "aticonfig-Device[0]-0" Driver "fglrx" BusID "PCI:0:1:0" Option "TexturedVideoSync" "on" Option "UseFastTLS" "2" EndSection Section "Screen" Identifier "aticonfig-Screen[0]-0" Device "aticonfig-Device[0]-0" Monitor "Monitor0" DefaultDepth 24 Option "UseEDID" "False" Option "ExactModeTimingsDVI" "True" Option "NoBandWidthTest" "true" Option "ModeValidation" "AllowNon60hzmodesDFPModes, NoEDIDDFPMaxSizeCheck, NoVertRefreshCheck, NoHorizSyncCheck, NoDFPNativeResolutionCheck, NoMaxSizeCheck, NoMaxPClkCheck, NoEDIDModes" Option "UseEDIDDPI" "False" Option "UseEDIDFreqs" "0" Option "NoLogo" "True" Option "Coolbits" "1" Option "metamodes" "DFP-0: 2560x1440_60 +0+0" SubSection "Display" Depth 24 Modes "2560x1440" EndSubSection I ran memtest on my ram and it checks out fine. I have tried using the latest fglrx and fglrx-beta. I have loaded 3.6.x kernel. I do not see anything relevant in dmesg, kern.log, syslog, .xsession-errors or Xorg.log. I cannot ssh into the machine when frozen from another machine. I know that system resources not being stressed when the crashes happen. It seems that video and any gaming (very simple graphics games) contribute to the freezes most frequently. However, I have experienced the crash before when just using Chrome. I suspect the crashes are xorg/fglrx related, but I have no evidence to back that up. Where should I look? What should I grep for? What should I try next?

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• Can't boot after compiling 3.1 kernel, can only get to terminal

  - by olssy

  Long story short: I tried compiling kernel 3.1 on Ubuntu 11.10 at the same time I had an update waiting for a reboot. Computer would boot to a black screen and would hang there. Ended up installing 11.10 on top of old install with a Live CD. Now I had a purple screen on bootup but it would end up booting. Realized Grub was the problem and tried some stuff but nothing worked. I ended up trying to install propriety ATI video drivers and since that nothing has worked, no grub menu(purple screen) and when it boots into the kernel it ends up hanging, I can sometimes get a terminal up with alt-fx. I have tried removing the ati drivers with the ati script, purging my fglrx driver, reconfiguring my xconf.org and following any tutorial I can find about fixing a broken graphics driver, but to no avail. I've gotten to a point were it seems that the ati propriety drivers are correctly loaded but it still has no grub boot menu and won't boot into Ubuntu. I've chased down my logs and this line is from kern.log: unity-greeter[3269]: segfault at 0 ip b7245cbbsp bf9d3900 error 4 in libgio-2.0.so.0.3000.0[b71ad000+142000] That line leads me to believe I don'T have the correct libgio-2 librairy on my system but have no idea how to find out what package has the correct version... My xorg.conf has no errors and seems to imply the fglrxdrm module got loaded correctly. Would be a bit complicated pasting the whole file here but if it would help I'll post it. LAstly, running fglrxinfo give me: Error: Unable yo open display (null) Any help or link to another tutorial would be appreciated. Thanks.

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• Ubuntu 11.10 Random reboots how to find root cause?

  - by Indigo42

  All, This issue started with 11.04, I upgraded to 11.10 this week in hopes it would correct it, but after a few days it happened again.. A few times a day, randomly, my monitors will go black and the machine will come back in the post screen and boot up again. Sometimes it boots up properly, sometimes it boots to disk scan (I understand why...the machine just died with a bunch of stuff open) and sometimes it takes several cycles of this to come up. I connected to the system with my laptop and tailed dmesg, syslog, kern.log, and Xorg.0.log. I also ran a cat /proc/kmesg. Nothing is showing up in any of these log files when it happens..it's just like someone has pulled the plug. I just got through running 4 hours of the memory test with no errors. I have a AMD Phenom 9850 Quad-Core Processor and Nvida 9500GT graphics card. This system has been stable for like 4 years. I'm thinking it might be a hardware problem, but how do I find out? Thanks,

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• Anonymous Methods / Lambda's (Coding Standards)

  - by Mystagogue

  In Jeffrey Richter's "CLR via C#" (the .net 2.0 edtion page, 353) he says that as a self-discipline, he never makes anonymous functions longer than 3 lines of code in length. He cites mostly readability / understandability as his reasons. This suites me fine, because I already had a self-discipline of using no more than 5 lines for an anonymous method. But how does that "coding standard" advice stack against lambda's? At face value, I'd treat them the same - keeping a lambda equally as short. But how do others feel about this? In particular, when lambda's are being used where (arguably) they shine brightest - when used in LINQ statements - is there genuine cause to abandon that self-discipline / coding standard?

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• NHibernate session management in ASP.NET MVC

  - by Kevin Pang

  I am currently playing around with the HybridSessionBuilder class found on Jeffrey Palermo's blog post: http://jeffreypalermo.com/blog/use-this-nhibernate-wrapper-to-keep-your-repository-classes-simple/ Using this class, my repository looks like this: public class UserRepository : IUserRepository { private readonly ISessionBuilder _sessionBuilder; public UserRepository(ISessionBuilder sessionBuilder) { _sessionBuilder = sessionBuilder; } public User GetByID(string userID) { using (ISession session = _sessionBuilder.GetSession()) { return session.Get<User>(userID); } } } Is this the best way to go about managing the NHibernate session / factory? I've heard things about Unit of Work and creating a session per web request and flushing it at the end. From what I can tell, my current implementation isn't doing any of this. It is basically relying on the Repository to grab the session from the session factory and use it to run the queries. Are there any pitfalls to doing database access this way?

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• Does delegate chaining have to start with a null Delegate?

  - by MCS

  In CLR via C#, Jeffrey Richter gives the following example of delegate chaining (pg. 406): internal delegate void Feedback(Int 32 value); Feedback fb1 = new Feedback(method1); // in the book, these methods Feedback fb2 = new Feedback(method2); // have different names Feedback fb3 = new Feedback(method3); Feedback fbChain = null; fbChain = (Feedback) Delegate.Combine(fbChain, fb1); fbChain = (Feedback) Delegate.Combine(fbChain, fb2); fbChain = (Feedback) Delegate.Combine(fbChain, fb3); Why does the first call to Delegate.Combine have to pass in a null Delegate? Here's how I would have thought it should be written: Feedback fbChain = (Feedback) Delegate.Combine(fb1, fb2); fbChain = (Feedback) Delegate.Combine(fbchain, fb3);

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• How to write a Compiler in C for C

  - by Kerb_z

  I want to write a Compiler for C. This is a Project for my College i am doing as per my University. I am an intermediate programmer in C, with understanding of Data Structures. Now i know a Compiler has the following parts: 1. Lexer 2. Parser 3. Intermediate Code Generator 4. Optimizer 5. Code Generator I want to begin with the Lexer part and move on to Parser. I am consulting the following book: Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Ravi Sethi, Jeffrey D. Ullman. The thing is that this book is highly theoretical and perplexing to me. I really appreciate the authors. But the point is i am not able to begin my project, as if i am blinded where to go. Need guidance please help.

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• Ghost Records, Backups, and Database Compression…With a Pinch of Security Considerations

  - by Argenis

    Today Jeffrey Langdon (@jlangdon) posed on #SQLHelp the following questions: So I set to answer his question, and I said to myself: “Hey, I haven’t blogged in a while, how about I blog about this particular topic?”. Thus, this post was born. (If you have never heard of Ghost Records and/or the Ghost Cleanup Task, go see this blog post by Paul Randal) 1) Do ghost records get copied over in a backup? If you guessed yes, you guessed right. The backup process in SQL Server takes all data as it is on disk – it doesn’t crack the pages open to selectively pick which slots have actual data and which ones do not. The whole page is backed up, regardless of its contents. Even if ghost cleanup has run and processed the ghost records, the slots are not overwritten immediately, but rather until another DML operation comes along and uses them. As a matter of fact, all of the allocated space for a database will be included in a full backup. So, this poses a bit of a security/compliance problem for some of you DBA folk: if you want to take a full backup of a database after you’ve purged sensitive data, you should rebuild all of your indexes (with FILLFACTOR set to 100%). But the empty space on your data file(s) might still contain sensitive data! A SHRINKFILE might help get rid of that (not so) empty space, but that might not be the end of your troubles. You might _STILL_ have (not so) empty space on your files! One approach that you can follow is to export all of the data on your database to another SQL Server instance that does NOT have Instant File Initialization enabled. This can be a tedious and time-consuming process, though. So you have to weigh in your options and see what makes sense for you. Snapshot Replication is another idea that comes to mind. 2) Does Compression get rid of ghost records (2008)? The answer to this is no. The Ghost Records/Ghost Cleanup Task mechanism is alive and well on compressed tables and indexes. You can prove this running a simple script: CREATE DATABASE GhostRecordsTest GO USE GhostRecordsTest GO CREATE TABLE myTable (myPrimaryKey int IDENTITY(1,1) PRIMARY KEY CLUSTERED,                       myWideColumn varchar(1000) NOT NULL DEFAULT 'Default string value')                         ALTER TABLE myTable REBUILD PARTITION = ALL WITH (DATA_COMPRESSION = PAGE) GO INSERT INTO myTable DEFAULT VALUES GO 10 DELETE myTable WHERE myPrimaryKey % 2 = 0 DBCC TRACEON(2514) DBCC CHECKTABLE(myTable) TraceFlag 2514 will make DBCC CHECKTABLE give you an extra tidbit of information on its output. For the above script: “Ghost Record count = 5” Until next time,   -Argenis

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• Ghost Records, Backups, and Database Compression…With a Pinch of Security Considerations

  - by Argenis

    Today Jeffrey Langdon (@jlangdon) posed on #SQLHelp the following questions: So I set to answer his question, and I said to myself: “Hey, I haven’t blogged in a while, how about I blog about this particular topic?”. Thus, this post was born. (If you have never heard of Ghost Records and/or the Ghost Cleanup Task, go see this blog post by Paul Randal) 1) Do ghost records get copied over in a backup? If you guessed yes, you guessed right. The backup process in SQL Server takes all data as it is on disk – it doesn’t crack the pages open to selectively pick which slots have actual data and which ones do not. The whole page is backed up, regardless of its contents. Even if ghost cleanup has run and processed the ghost records, the slots are not overwritten immediately, but rather until another DML operation comes along and uses them. As a matter of fact, all of the allocated space for a database will be included in a full backup. So, this poses a bit of a security/compliance problem for some of you DBA folk: if you want to take a full backup of a database after you’ve purged sensitive data, you should rebuild all of your indexes (with FILLFACTOR set to 100%). But the empty space on your data file(s) might still contain sensitive data! A SHRINKFILE might help get rid of that (not so) empty space, but that might not be the end of your troubles. You might _STILL_ have (not so) empty space on your files! One approach that you can follow is to export all of the data on your database to another SQL Server instance that does NOT have Instant File Initialization enabled. This can be a tedious and time-consuming process, though. So you have to weigh in your options and see what makes sense for you. Snapshot Replication is another idea that comes to mind. 2) Does Compression get rid of ghost records (2008)? The answer to this is no. The Ghost Records/Ghost Cleanup Task mechanism is alive and well on compressed tables and indexes. You can prove this running a simple script: CREATE DATABASE GhostRecordsTest GO USE GhostRecordsTest GO CREATE TABLE myTable (myPrimaryKey int IDENTITY(1,1) PRIMARY KEY CLUSTERED,                       myWideColumn varchar(1000) NOT NULL DEFAULT 'Default string value')                         ALTER TABLE myTable REBUILD PARTITION = ALL WITH (DATA_COMPRESSION = PAGE) GO INSERT INTO myTable DEFAULT VALUES GO 10 DELETE myTable WHERE myPrimaryKey % 2 = 0 DBCC TRACEON(2514) DBCC CHECKTABLE(myTable) TraceFlag 2514 will make DBCC CHECKTABLE give you an extra tidbit of information on its output. For the above script: “Ghost Record count = 5” Until next time,   -Argenis

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• Plan Operator Tuesday round-up

  - by Rob Farley

  Eighteen posts for T-SQL Tuesday #43 this month, discussing Plan Operators. I put them together and made the following clickable plan. It’s 1000px wide, so I hope you have a monitor wide enough. Let me explain this plan for you (people’s names are the links to the articles on their blogs – the same links as in the plan above). It was clearly a SELECT statement. Wayne Sheffield (@dbawayne) wrote about that, so we start with a SELECT physical operator, leveraging the logical operator Wayne Sheffield. The SELECT operator calls the Paul White operator, discussed by Jason Brimhall (@sqlrnnr) in his post. The Paul White operator is quite remarkable, and can consume three streams of data. Let’s look at those streams. The first pulls data from a Table Scan – Boris Hristov (@borishristov)’s post – using parallel threads (Bradley Ball – @sqlballs) that pull the data eagerly through a Table Spool (Oliver Asmus – @oliverasmus). A scalar operation is also performed on it, thanks to Jeffrey Verheul (@devjef)’s Compute Scalar operator. The second stream of data applies Evil (I figured that must mean a procedural TVF, but could’ve been anything), courtesy of Jason Strate (@stratesql). It performs this Evil on the merging of parallel streams (Steve Jones – @way0utwest), which suck data out of a Switch (Paul White – @sql_kiwi). This Switch operator is consuming data from up to four lookups, thanks to Kalen Delaney (@sqlqueen), Rick Krueger (@dataogre), Mickey Stuewe (@sqlmickey) and Kathi Kellenberger (@auntkathi). Unfortunately Kathi’s name is a bit long and has been truncated, just like in real plans. The last stream performs a join of two others via a Nested Loop (Matan Yungman – @matanyungman). One pulls data from a Spool (my post – @rob_farley) populated from a Table Scan (Jon Morisi). The other applies a catchall operator (the catchall is because Tamera Clark (@tameraclark) didn’t specify any particular operator, and a catchall is what gets shown when SSMS doesn’t know what to show. Surprisingly, it’s showing the yellow one, which is about cursors. Hopefully that’s not what Tamera planned, but anyway...) to the output from an Index Seek operator (Sebastian Meine – @sqlity). Lastly, I think everyone put in 110% effort, so that’s what all the operators cost. That didn’t leave anything for me, unfortunately, but that’s okay. Also, because he decided to use the Paul White operator, Jason Brimhall gets 0%, and his 110% was given to Paul’s Switch operator post. I hope you’ve enjoyed this T-SQL Tuesday, and have learned something extra about Plan Operators. Keep your eye out for next month’s one by watching the Twitter Hashtag #tsql2sday, and why not contribute a post to the party? Big thanks to Adam Machanic as usual for starting all this. @rob_farley

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• Roll your own free .NET technical conference

  - by Brian Schroer

  If you can’t get to a conference, let the conference come to you! There are a ton of free recorded conference presentations online… Microsoft TechEd Let’s start with the proverbial 800 pound gorilla. Recent TechEds have recorded the majority of presentations and made them available online the next day. Check out presentations from last month’s TechEd North America 2012 or last week’s TechEd Europe 2012. If you start at http://channel9.msdn.com/Events/TechEd, you can also drill down to presentations from prior years or from other regional TechEds (Australia, New Zealand, etc.) The top presentations from my “View Queue”: Damian Edwards: Microsoft ASP.NET and the Realtime Web (SignalR) Jennifer Smith: Design for Non-Designers Scott Hunter: ASP.NET Roadmap: One ASP.NET – Web Forms, MVC, Web API, and more Daniel Roth: Building HTTP Services with ASP.NET Web API Benjamin Day: Scrum Under a Waterfall NDC The Norwegian Developer Conference site has the most interesting presentations, in my opinion. You can find the videos from the June 2012 conference at that link. The 2011 and 2010 pages have a lot of presentations that are still relevant also. My View Queue Top 5: Shay Friedman: Roslyn... hmmmm... what? Hadi Hariri: Just ‘cause it’s JavaScript, doesn’t give you a license to write rubbish Paul Betts: Introduction to Rx Greg Young: How to get productive in a project in 24 hours Michael Feathers: Deep Design Lessons ØREDEV Travelling on from Norway to Sweden... I don’t know why, but the Scandinavians seem to have this conference thing figured out. ØREDEV happens each November, and you can find videos here and here. My View Queue Top 5: Marc Gravell: Web Performance Triage Robby Ingebretsen: Fonts, Form and Function: A Primer on Digital Typography Jon Skeet: Async 101 Chris Patterson: Hacking Developer Productivity Gary Short: .NET Collections Deep Dive aspConf - The Virtual ASP.NET Conference Formerly known as “mvcConf”, this one’s a little different. It’s a conference that takes place completely on the web. The next one’s happening July 17-18, and it’s not too late to register (It’s free!). Check out the recordings from February 2011 and July 2010. It’s two years old and talks about ASP.NET MVC2, but most of it is still applicable, and Jimmy Bogard’s Put Your Controllers On a Diet presentation is the most useful technical talk I have ever seen. CodeStock Videos from the 2011 edition of this Tennessee conference are available. Presentations from last month’s 2012 conference should be available soon here. I’m looking forward to watching Matt Honeycutt’s Build Your Own Application Framework with ASP.NET MVC 3. UserGroup.tv User Group.tv was founded in January of 2011 by Shawn Weisfeld, with the mission of providing User Group content online for free. You can search by date, group, speaker and category tags. My View Queue Top 5: Sergey Rathon & Ian Henehan: UI Test Automation with Selenium Rob Vettor: The Repository Pattern Latish Seghal: The .NET Ninja’s Toolbelt Amir Rajan: Get Things Done With Dynamic ASP.NET MVC Jeffrey Richter: .NET Nuggets – Houston TechFest Keynote

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• External USB attached drive works in Windows XP but not in Windows 7. How to fix?

  - by irrational John

  Earlier this week I purchased this "N52300 EZQuest Pro" external hard drive enclosure from here. I can connect the enclosure using USB 2.0 and access the files in both NTFS partitions on the MBR partitioned drive when I use either Windows XP (SP3) or Mac OS X 10.6. So it works as expected in XP & Snow Leopard. However, the enclosure does not work in Windows 7 (Home Premium) either 64-bit or 32-bit or in Ubuntu 10.04 (kernel 2.6.32-23-generic). I'm thinking this must be a Windows 7 driver problem because the enclosure works in XP & Snow Leopard. I do know that no special drivers are required to use this enclosure. It is supported using the USB mass storage drivers included with XP and OS X. It should also work fine using the mass storage support in Windows 7, no? FWIW, I have also tried using 32-bit Windows 7 on both my desktop, a Gigabyte GA-965P-DS3 with a Pentium Dual-Core E6500 @ 2.93GHz, and on my early 2008 MacBook. I see the same failure in both cases that I see with 64-bit Windows 7. So it doesn't appear to be specific to one hardware platform. I'm hoping someone out there can help me either get the enclosure to work in Windows 7 or convince me that the enclosure hardware is bad and should be RMAed. At the moment though an RMA seems pointless since this appears to be a (Windows 7) device driver problem. I have tried to track down any updates to the mass storage drivers included with Windows 7 but have so far come up empty. Heck, I can't even figure out how to place a bug report with Microsoft since apparently the grace period for Windows 7 email support is only a few months. I came across a link to some USB troubleshooting steps in another question. I haven't had a chance to look over the suggestions on that site or try them yet. Maybe tomorrow if I have time ... ;-) I'll finish up with some more details about the problem. When I connect the enclosure using USB to Windows 7 at first it appears everything worked. Windows detects the drive and installs a driver for it. Looking in Device Manager there is an entry under the Hard Drives section with the title, Hitachi HDT721010SLA360 USB Device. When you open Windows Disk Management the first time after the enclosure has been attached the drive appears as "Not initialize" and I'm prompted to initialize it. This is bogus. After all, the drive worked fine in XP so I know it has already been initialized, partitioned, and formatted. So of course I never try to initialize it "again". (It's a 1 GB drive and I don't want to lose the data on it). Except for this first time, the drive never shows up in Disk Management again unless I uninstall the Hitachi HDT721010SLA360 USB Device entry under Hard Drives, unplug, and then replug the enclosure. If I do that then the process in the previous paragraph repeats. In Ubuntu the enclosure never shows up at all at the file system level. Below are an excerpt from kern.log and an excerpt from the result of lsusb -v after attaching the enclosure. It appears that Ubuntu at first recongnizes the enclosure and is attempting to attach it, but encounters errors which prevent it from doing so. Unfortunately, I don't know whether any of this info is useful or not. excerpt from kern.log [ 2684.240015] usb 1-2: new high speed USB device using ehci_hcd and address 22 [ 2684.393618] usb 1-2: configuration #1 chosen from 1 choice [ 2684.395399] scsi17 : SCSI emulation for USB Mass Storage devices [ 2684.395570] usb-storage: device found at 22 [ 2684.395572] usb-storage: waiting for device to settle before scanning [ 2689.390412] usb-storage: device scan complete [ 2689.390894] scsi 17:0:0:0: Direct-Access Hitachi HDT721010SLA360 ST6O PQ: 0 ANSI: 4 [ 2689.392237] sd 17:0:0:0: Attached scsi generic sg7 type 0 [ 2689.395269] sd 17:0:0:0: [sde] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB) [ 2689.395632] sd 17:0:0:0: [sde] Write Protect is off [ 2689.395636] sd 17:0:0:0: [sde] Mode Sense: 11 00 00 00 [ 2689.395639] sd 17:0:0:0: [sde] Assuming drive cache: write through [ 2689.412003] sd 17:0:0:0: [sde] Assuming drive cache: write through [ 2689.412009] sde: sde1 sde2 [ 2689.455759] sd 17:0:0:0: [sde] Assuming drive cache: write through [ 2689.455765] sd 17:0:0:0: [sde] Attached SCSI disk [ 2692.620017] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2707.740014] usb 1-2: device descriptor read/64, error -110 [ 2722.970103] usb 1-2: device descriptor read/64, error -110 [ 2723.200027] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2738.320019] usb 1-2: device descriptor read/64, error -110 [ 2753.550024] usb 1-2: device descriptor read/64, error -110 [ 2753.780020] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2758.810147] usb 1-2: device descriptor read/8, error -110 [ 2763.940142] usb 1-2: device descriptor read/8, error -110 [ 2764.170014] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2769.200141] usb 1-2: device descriptor read/8, error -110 [ 2774.330137] usb 1-2: device descriptor read/8, error -110 [ 2774.440069] usb 1-2: USB disconnect, address 22 [ 2774.440503] sd 17:0:0:0: Device offlined - not ready after error recovery [ 2774.590023] usb 1-2: new high speed USB device using ehci_hcd and address 23 [ 2789.710020] usb 1-2: device descriptor read/64, error -110 [ 2804.940020] usb 1-2: device descriptor read/64, error -110 [ 2805.170026] usb 1-2: new high speed USB device using ehci_hcd and address 24 [ 2820.290019] usb 1-2: device descriptor read/64, error -110 [ 2835.520027] usb 1-2: device descriptor read/64, error -110 [ 2835.750018] usb 1-2: new high speed USB device using ehci_hcd and address 25 [ 2840.780085] usb 1-2: device descriptor read/8, error -110 [ 2845.910079] usb 1-2: device descriptor read/8, error -110 [ 2846.140023] usb 1-2: new high speed USB device using ehci_hcd and address 26 [ 2851.170112] usb 1-2: device descriptor read/8, error -110 [ 2856.300077] usb 1-2: device descriptor read/8, error -110 [ 2856.410027] hub 1-0:1.0: unable to enumerate USB device on port 2 [ 2856.730033] usb 3-2: new full speed USB device using uhci_hcd and address 11 [ 2871.850017] usb 3-2: device descriptor read/64, error -110 [ 2887.080014] usb 3-2: device descriptor read/64, error -110 [ 2887.310011] usb 3-2: new full speed USB device using uhci_hcd and address 12 [ 2902.430021] usb 3-2: device descriptor read/64, error -110 [ 2917.660013] usb 3-2: device descriptor read/64, error -110 [ 2917.890016] usb 3-2: new full speed USB device using uhci_hcd and address 13 [ 2922.911623] usb 3-2: device descriptor read/8, error -110 [ 2928.051753] usb 3-2: device descriptor read/8, error -110 [ 2928.280013] usb 3-2: new full speed USB device using uhci_hcd and address 14 [ 2933.301876] usb 3-2: device descriptor read/8, error -110 [ 2938.431993] usb 3-2: device descriptor read/8, error -110 [ 2938.540073] hub 3-0:1.0: unable to enumerate USB device on port 2 excerpt from lsusb -v Bus 001 Device 017: ID 0dc4:0000 Macpower Peripherals, Ltd Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x0dc4 Macpower Peripherals, Ltd idProduct 0x0000 bcdDevice 0.01 iManufacturer 1 EZ QUEST iProduct 2 USB Mass Storage iSerial 3 220417 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 5 Config0 bmAttributes 0xc0 Self Powered MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 8 Mass Storage bInterfaceSubClass 6 SCSI bInterfaceProtocol 80 Bulk (Zip) iInterface 4 Interface0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0001 Self Powered Update: Results using Firewire to connect. Today I recieved a 1394b 9 pin to 1394a 6 pin cable which allowed me to connect the "EZQuest Pro" via Firewire. Everything works. When I use Firewire I can connect whether I'm using Windows 7 or Ubuntu 10.04. I even tried booting my Gigabyte desktop as an OS X 10.6.3 Hackintosh and it worked there as well. (Though if I recall correctly, it also worked when using USB 2.0 and booting OS X on the desktop. Certainly it works with USB 2.0 and my MacBook.) I believe the firmware on the device is at the latest level available, v1.07. I base this on the excerpt below from the OS X System Profiler which shows Firmware Revision: 0x107. Bottom line: It's nice that the enclosure is actually usable when I connect with Firewire. But I am still searching for an answer as to why it does not work correctly when using USB 2.0 in Windows 7 (and Ubuntu ... but really Windows 7 is my biggest concern). OXFORD IDE Device 1: Manufacturer: EZ QUEST Model: 0x0 GUID: 0x1D202E0220417 Maximum Speed: Up to 800 Mb/sec Connection Speed: Up to 400 Mb/sec Sub-units: OXFORD IDE Device 1 Unit: Unit Software Version: 0x10483 Unit Spec ID: 0x609E Firmware Revision: 0x107 Product Revision Level: ST6O Sub-units: OXFORD IDE Device 1 SBP-LUN: Capacity: 1 TB (1,000,204,886,016 bytes) Removable Media: Yes BSD Name: disk3 Partition Map Type: MBR (Master Boot Record) S.M.A.R.T. status: Not Supported

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• Where does output of print in kernel go?

  - by apoorv020

  I am debugging a driver for linux (specifically ubuntu server 9.04), and there are several printf statements in the code. Where can I view the output of these statements? EDIT1: What i'm trying to do is write to kernel using the proc file-system. The print code is static int proc_fractel_config_write(struct file *file, const char *argbuf, unsigned long count, void *data) { printk(KERN_DEBUG "writing fractel config\n"); ... In kern.log when I see the following message when i try to overwrite the file /proc/net/madwifi/ath1/fractel_config (with varying time of course). [ 8671.924873] proc write [ 8671.924919] Any explainations?

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• System crashes/lockups + compiz/cairo/gnome-panel crashing due to cached ram, please help?

  - by Kristian Thomson

  Can someone help me to troubleshoot system crashes and lockups which result in compiz/cairo dock and gnome-panel crashing? I also get no window borders after the crash and a lot of kernel memory errors. Logs are telling me that apps were killed due to not enough memory, but the system is caching like 14GB of my ram so I'm a bit stuck on what/how to stop it. I'm running Ubuntu 12.10 on a 2011 Mac Mini with 16 GB ram. Here's some of the logs that look like they could be causing trouble. I woke up this morning to find chrome/skype/cairo dock and a few others had been killed and here is what the log said. Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.959890] Out of memory: Kill process 12247 (chromium-browse) score 101 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.959893] Killed process 12247 (chromium-browse) total-vm:238948kB, anon-rss:17064kB, file-rss:20008kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.972283] Out of memory: Kill process 10976 (dropbox) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.972288] Killed process 10976 (dropbox) total-vm:316392kB, anon-rss:115484kB, file-rss:16504kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.975890] Out of memory: Kill process 10887 (rhythmbox) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.975895] Killed process 11515 (tray_icon_worke) total-vm:63336kB, anon-rss:15960kB, file-rss:11436kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.281535] Out of memory: Kill process 10887 (rhythmbox) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.281539] Killed process 10887 (rhythmbox) total-vm:528980kB, anon-rss:92272kB, file-rss:36520kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.283110] Out of memory: Kill process 10889 (skype) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.283113] Killed process 10889 (skype) total-vm:415056kB, anon-rss:84880kB, file-rss:22160kB I went to look deeper into things and saw that the whole time I'm having these kernel errors with out of memory and something mentioning radeon. I have a Radeon HD 6600M graphics card using the open source driver, not the proprietary one. I was wondering if perhaps using the proprietary one would solve the problem. Also, while writing this in Chrome rhythmbox and chrome just got killed while typing this, due to out of memory errors or so it reports, though I have 7 GB of free RAM at the time with 7 GB cached as well. Here is a full copy of my logs that happened in kern.log simply from when I began typing this question. http://pastebin.com/cdxxDktG Thanks in advance, Kris

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• SATA drives or chipset throwing DRDY ERR and ICRC ABRT

  - by Matt

  I have an SD-VIA-1A2S PCI card with 2 sata ports (and one ATA-133 that isn't used). Two new Western Digital Caviar Green drives (WD10EARS 1TB) throw repeated errors in kern.log (removed date/time/host info for brevity): [ 7.376475] ata2.00: exception Emask 0x12 SAct 0x0 SErr 0x1000500 action 0x6 [ 7.376480] ata2.00: BMDMA stat 0x5 [ 7.376483] ata2: SError: { UnrecovData Proto TrStaTrns } [ 7.376489] ata2.00: cmd c8/00:40:20:00:00/00:00:00:00:00/e0 tag 0 dma 32768 in [ 7.376490] res 51/84:2f:20:00:00/00:00:00:00:00/e0 Emask 0x12 (ATA bus error) [ 7.376493] ata2.00: status: { DRDY ERR } [ 7.376495] ata2.00: error: { ICRC ABRT } [ 7.376504] ata2: hard resetting link I'm using Ubuntu 9.04 - 2.6.28-18-generic, though I have tried live cds of Ubuntu 9.10, Fedora 12 and OpenSUSE 11.2 - all running various 2.6.31 kernels - and all received the same error. Based on testing these drives and this card in two other machines and combos of connecting the drives directly to the motherboard or the add-in card, I'm relatively convinced that it's the VIA chipset that is the problem. Another computer that also has an onboard VIA SATA chipset (like the add-in card) produces the same errors when the drives are directly on that motherboard. I have been able to verify that the drives are perfectly good, and I tried everything I can think of in terms of swapping cables, psu isn't overloaded, etc. The error happens on boot once or twice, after using fdisk on the drive once or twice, and constantly when attempting to sync a new mdadm raid 1 array created on the two drives. Any thoughts on where to go from here - driver/kernel wise? I'm completely open to buying a new PCI add-in card if someone can recommend one with 2 internal sata ports that works well in Debian/Ubuntu. Thanks!

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