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• i7-980X at 70% speed

  - by Buxley

  Hi we bought a nice computer to use to solve optimization problems. Intel i7-980X@3,33 GHz with 12 GB of Team Group 1600 MHz DDR3 RAM. When we use Gurobi the computer uses all 12 cores at maximum in the beginning of the solve. However after a while (about 8 hrs) it all cores jump between 65 and 85% When I solve the same models on an i7 930 all cores are at a near 100% level even after longer solution times. We first thought that the Hard disk was the bottleneck since Gurobi writes out nodefiles after the memorylimit is used. However since the new computer have 12 GB of RAM we put the memorylimit to 7 GB so the solver only used the RAM and still with the same performance in the processor. Any ideas about the bottleneck? As I said earlier it works at 100% for the first hours or so . Thanks very much for any answers! Our plan was to overclock it but we can't even get it to work at normal speed yet!

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• Last step in HDD Recovery (fixing windows)

  - by Atom Computing

  My dad’s hard drive corrupted which was a result of many bad sectors. Anyway, I made a clone of the drive and have now repaired it totally (recreating the MBR and MFT) and doing a series of ChkDsk's on it. I can now see all the files and folder on it and it is all intact. I currently have it as a slave in my computer (where I was doing all the repairs). When putting it back into the computer, it comes up with "A disk read error occurred: Press Ctrl + Alt + Del to Restart". I don’t know why this is happening but think it might have something to do with file permissions. I have tried a start-up recovery on the Vista boot CD and it found no problems. When trying to apply file permissions (and creating file perms for the SYSTEM group (as it didn’t have any for SYSTEM group)) it couldn't apply them for some of the System32 folder files. I have tried applying them as admin and with as powerful privileges I can get. All to no avail. When it is in my PC I can boot it up (I added it into my bootloader) and it boots up fine except when it logs in it comes up with the error - "Rundll32.exe - Windows cannot access the specified device, path or file. You may not have the appropriate permissions to access the item" This message keeps coming back and nothing loads at all. Any help would be greatly received as I have got so far with the data recovery and want to avoid a reformat at all costs due to the vast number of programs installed and I don’t have much time on my hands! Thanks

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• What can be a reason for phpMyAdmin login to be not working (not at all, no reaction on submit)?

  - by Ivan

  When I open "http://localhost/phpmyadmin/", enter "root" as the user name and my MySQL root password and press go, then if I was using Firefox, I was getting offered to download index.php file (of a zero length), if I was using Opera 11, it said "Connection closed by remote server". Following recommendations I've removed all packages related to phpMyAdmin, PHP, MySQL and Apache and then reinstalled them step-by step (instead of just issuing apt-get install phpmyadmin and relying on the system to install the whole LAMP stack via dependencies as I've done before). The only change I've got was Firefox to stop offering to download index.php - now when I press Ok to submit my password, it just doesn't show any visible reaction at all. What may the reason be and how to fix it? I use up-to-date Xubuntu 11.04. Reinstalling the whole LAMP stack and phpMyAdmin did not help, neither did removing AppArmor. I've tried to use SQLBuddy instead, but there's exactly the same problem. So, I think, the problem is not in phpMyAdmin but in MySQL, Apache or something. MySQL seems to work if I use command line to access it. Apache & PHP seems to work also, as the login page of phpMyAdmin displays correctly.

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• How to recover Windows Password without reinstalling if you forgot Windows password?

  - by user38908

  Usually, we can recover Windows admin password in two traditional ways. The first is to change Windows password with another admin account; the second is to recover the previous password with the windows password reset disk that had been created before you forgot the password. Take Windows XP for example, 1 At the Windows XP login prompt when the password is entered incorrectly click the reset button in the login failed window. 2 Insert the password reset diskette into the computer and click Next. 3 If the correct diskette Windows XP will open a window prompting for the new password you wish to use. However, we offen ignore the important of security until we have been locked out of computer. Fortunately, there is still the last way that can unlock your computer without reinstalling - erase Windows password with Windows password reset CD, which can recover admin password for Windows 7/XP/Vista/NT/2000/2003.... Take Windows Password unlocker for example, followings are the steps to create the reset CD 1.Download Windows Password Unlocker from Password Unlocker Official site 2.Decompress the Windows password unlocker and note that there is an .ISO image file. Burn the image file onto an blank CD with the burner freely supported by Password Unlocker. 3.Insert the newly created CD into the locked computer and re-boot it from the CD drive. 4.After launched the CD, a window pop up with all your account names(if you have several accounts) select one of the accounts that you have forgotten its password to reset it. Just one press, this software can remove Windows password instantly.

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• Volume is no longer showing in Raid Controller BIOS and in Windows

  - by Gordon

  Hi all, I have installed some critical Windows Updates yesterday and now my external RAID Volume no longer shows in Windows Vista x64. All updates went through successfully. From their description, I cannot see how they should relate to the issue, but this is the only change that happened, so who knows. Anyway, here is the details: I have an external eSata enclosure that is running on a SiI4726 controller. I can connect to the controller with it's management utility from the computer the enclosure is connected to. The three drives in the enclosure show up as JBODs. I had those drives configured to be one logical RAID5 drive. RAID management is done through a SiI3132 SoftRaid controller. The Raid Management Utility just shows empty channels where it usually shows the Raid Group. In the Windows Disk Manager, I can see an unknown unitialized device. This is fine according to the setup manual. What it doesn't show is my Raid drive. It's gone. Also, when booting Windows, the BIOS of the controller used to show the RAID volume before booting the OS. This is not happening anymore. Updating drivers and firmware did not help. I have made sure the drivers and firmware are compatible to each others. And like I said, it used to work before. Any clues?

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• Network driver for Hyper-V restore from Windows Home Server

  - by Philipp Schmid

  I have backed up Windows Server 2008 running virtualized on Hyper-V to a Windows Home Server 2008 SP1 (I know I should have backed up the VHD instead). Now I need to restore the contents of the VM from WHS. I have created a restore CD ISO and used it to create a new VM. It all works as advertised up to the point where the restore process wants to load the network drivers (it only finds 4 disk drivers on the restore CD. but no network drivers). So I created a virtual floppy and copied the contents of 'Home Server Drivers for Restore onto it. But no luck! I have tried moving the 4 subdirectories into the root of the floppy, but that didn't work either. Finally, I started another instance of the WS 2008 to identify the network driver that the virtualized instance is using (%WINDOWS%\system32\drivers\netvsc60.sys) and copied that file onto the virtual floppy, without success. Does anyone have any suggestions on how to get networking working on a Hyper-V instance running off the Windows Home Server Restore CD? UPDATE: As suggested by delenda, I have added a legacy network adapter to my VM, and indeed I now get a network driver listed! However, the WHS it still not found, even after entering the home server name manually. PHS

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• maximum size filesystem on my test .... approach?

  - by jocco

  Hello all I'm new at the site, and I have a question. I got this question at a test and really like to know the correct approach to solving this problem? Here is the question. In an indexed filesystem the first indexblock (inode) has 12 direct pointers and 1 pointer to an indirect indexblock. The filesystem is implemented on a disk with a diskblock-size of 1024 bytes. All pointers are 32 bit. Question: what is the maximum filesize (Kilobytes) of this filesystem? If it's possible not an just an answer but an explanation. edit: It was a multiple choice btw with 4 answers a. 13 K b. 268 K c. 524 K d. 1036 K As for my approach I only got as far as to know that 1 pointer is 32 bit Also I found something else here on the site which seems very usefull. http://stackoverflow.com/questions/2755006/understanding-the-concept-of-inodes Ok i got this far There are 12 blocks and each block is 1024 bytes. 1024 * 12 = 12288 bytes or 12 KB directly accessible. Please correct me if I'm wrong. Each pointer is 32 Bit = 4Byte And to be honest at this point I'm starting to get confused especially since my answer is way over any of my multiple choice answers.

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• Website latency and bad tcp packets

  - by Mistero Lupo

  I have multiple websites hosted on a Linode VPS and I'm having an issue with one of them: every page that I try to load has about 10 seconds latency. Apache logs are clean and the other websites on the same machine are running well. At a first glance I tought it was a memory problem since the VPS has got only 512M, but from the linode dashboard CPU and Disk I/O are normal. Anyway here we have the ram status: $ free -m total used free shared buffers cached Mem: 487 463 23 0 2 55 -/+ buffers/cache: 404 82 Swap: 255 155 100 Only 23M free, but if it was a memory problem why other websites are going as usual? I took a live capture with wireshark, and there are some duplicates SYN ACK packets just before the 10 seconds gap. I'm out of ideas, looking for some clues. Wireshark live capture screenshot As you can see from the image, the gap is after the last bad tcp. Thank you in advance. UPDATE I've checked Apache2 logs in debug error level, and this is where something is appening: 151.97.156.191 - - [14/Nov/2012:11:19:40 +0100] [www.fmaisi.it/sid#7f32c625a220][rid#7f32c6801578/subreq] (3) [perdir /home/fmaisi/sites/www.fmaisi.it/public_html/] applying pattern '^index\.php$' to uri 'index.php' 151.97.156.191 - - [14/Nov/2012:11:19:40 +0100] [www.fmaisi.it/sid#7f32c625a220][rid#7f32c6801578/subreq] (1) [perdir /home/fmaisi/sites/www.fmaisi.it/public_html/] pass through /home/fmaisi/sites/www.fmaisi.it/public_html/index.php 151.97.156.191 - - [14/Nov/2012:11:19:54 +0100] [www.fmaisi.it/sid#7f32c625a220][rid#7f32c6537c78/initial] (3) [perdir /home/fmaisi/sites/www.fmaisi.it/public_html/] strip per-dir prefix: /home/fmaisi/sites/www.fmaisi.it/public_html/wp-content/plugins/wp-filebase/wp-filebase_css.php -> wp-content/plugins/wp-filebase/wp-filebase_css.php 151.97.156.191 - - [14/Nov/2012:11:19:54 +0100] [www.fmaisi.it/sid#7f32c625a220][rid#7f32c6537c78/initial] (3) [perdir /home/fmaisi/sites/www.fmaisi.it/public_html/] applying pattern '^index\.php$' to uri 'wp-content/plugins/wp-filebase/wp-filebase_css.php' As you can see there is a gap of 14 seconds after the pass through of index.php. Any suggestions? I'm out of ideas again.

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• Cannot install windows. Compaq Presario CQ62

  - by Matthew

  I bought a used Compaq Presario CQ62 for cheap, and went to install windows on it. I formatted the partition and went to install when I got this error.... Windows cannot install required files. The file may be corrupt or missing. Make sure all files required for installation are available and restart the installation. Error code: 0x80070017 I have used this disk before with no problems, but internet searching suggested I burn one at 2x speed because that helps for some reason... I'm burning one now, but my question is, why would I get this error, OTHER than the disc being bad? I'm pretty certain this one isn't as I have used it before... (ok so the slowly burned cd (using imgburn) didn't work either so it's DEFINITELY not the disc) Thanks in advanced for any answers Also I took one stick of ram out because internet searching also suggested that, but it didn't make a difference. Also I ran memory and hard drive checks and they passed fine. Also I reset the motherboard options to default What could it be!? Help I'm completely stumped...

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• What should I encrypt in Debian during install?

  - by ianfuture

  I have seen various guides and recommendations on web about how best to do this but nothing that clearly explains the best way and why. So I understand there is a need for part of Debian during install to be un-encrypted on its own partition to allow it to boot. Most info I have seen is call this /boot and set the boot flag. Next I believe the best approach is to create another partition out of all the rest of the disk space, encrypt this, then on top of that create a LVM and then within the LVM create my various partitions , name them , select size, and file system type. Can I include /swap in the encrypted LVM part ? Is this approach sound? If so what are the partitions I should use (this is going to be a minimal server install with a view to install as and when what I need for a dev server)? Finally how does the installer know what to put in each partition I define ? I appreciate there are more than one question but any help and suggestions would be appreciated. If further clarification is needed please mention in the comments . EDIT : 16/3/2010 After Richard Holloways reply I thought it relevant to add this info: The reasons why I want to do this are to explore maximising security on any server install and set up, due to interest in the area of Computer Security and Forensics. Also I am trying to peform the task as if it being performed in an enterprise situation. On a technical matter, once set up and configured with minimal packages and ssh this server will not physically be easy to access so I will only be entering via ssh. (Yes I know why encrypt something no one will ever be able to get their hands on? Because I can and I want to is the simple answer, but see above too).

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• Java constructor using generic types

  - by user37903

  I'm having a hard time wrapping my head around Java generic types. Here's a simple piece of code that in my mind should work, but I'm obviously doing something wrong. Eclipse reports this error in BreweryList.java: The method initBreweryFromObject() is undefined for the type <T> The idea is to fill a Vector with instances of objects that are a subclass of the Brewery class, so the invocation would be something like: BreweryList breweryList = new BreweryList(BrewerySubClass.class, list); BreweryList.java package com.beerme.test; import java.util.Vector; public class BreweryList<T extends Brewery> extends Vector<T> { public BreweryList(Class<T> c, Object[] j) { super(); for (int i = 0; i < j.length; i++) { T item = c.newInstance(); // initBreweryFromObject() is an instance method // of Brewery, of which <T> is a subclass (right?) c.initBreweryFromObject(); // "The method initBreweryFromObject() is undefined // for the type <T>" } } } Brewery.java package com.beerme.test; public class Brewery { public Brewery() { super(); } protected void breweryMethod() { } } BrewerySubClass.java package com.beerme.test; public class BrewerySubClass extends Brewery { public BrewerySubClass() { super(); } public void androidMethod() { } } I'm sure this is a complete-generics-noob question, but I'm stuck. Thanks for any tips!

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• System randomly freezes yet mouse still moves

  - by user784446

  This problem has lasted for the past 48 hours. The first time it happened, a program I was running stopped responding, so I tried to end it from task manager. The processes at first were listed fine until hovered upon. Eventually, despite the mouse still being able to move, after a few persisting clicks the mouse finally stopped moving. The screen went blank shortly thereafter. The second time it occurred, items on the screen stopped responding - hovering over the taskbar or such wouldn't elicit a response. Sound would still play however. Eventually, the mouse became unresponsive and the system restarted itself. I suspect that it may be a problem of my SSD drive. After looking through some Google search results, I downloaded HDTunePro to determine if there's a problem with the drive. Results returned a problem of reallocated sector count. An error scan also revealed 48 bad sectors. Also, an attempt to backup the contents of the most important areas of the drive returned a few explorer "Error: cannot read source from disk" errors. Should I ditch the drive and use another drive or is there anything that can be done to repair the drive? SSD: OCZ Petrol 64gb CPU: AMD Athlon II X4 640 RAM: Generic 3GB DDR2 Motherboard: Gigabyte MA74GM-S2H OS: Windows 7 Ultimate x64 Thanks!

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• Strange boot problems on 6 month old setup

  - by Balefire

  I've already exhausted my knowledge on this one, so forgive me if this post is a bit long. I built a computer 6 months ago for my wife and it worked fine until last week. Then it randomly shut down and would lock up while trying to boot on the boot screen. I cleared cmos and it allowed me to do startup recovery, but it "failed to fix the issue" so I reinstalled windows on the HD (moving the old install to windows_old). It worked, so I started installing drivers again, but then when I restarted to finalize installations it locked up again. This time, I took the hard drive and hooked it up to my computer, backed up all her files, and then formatted the hard drive before reinstalling it. (again had to clear cmos to let me boot from disk) It installed windows, I installed drivers, and it worked for a few hours but then died during startup again. So, then I got a new HD, cleared cmos, and installed clean again, with the same result as the time before, it worked for a few hours, installed windows updates, then crashed on the 3rd or 4th time turning it on. I decided next to try reinstalling and then going online to see if there were any updates for the BIOS or drivers on the Motherboard, but now I can't get it to even bring up the boot menu, so now I'm just left wondering was it the motherboard, or is it the CPU, or the RAM? The problem was strangely intermittent so I thought it had to be a software issue, since a hardware issue would ALWAYS fail to boot, right? But now it seems to be a hardware issue, because it's not bringing up anything. Any suggestions? System: Windows 7 64-bit 970A-DS3 Gigabyte Motherboard AMD Phenom II X4 955 Deneb 3.2GHz Quad core Proc GeForce GT 430 (Fermi) 1GB Video Card 500W PSU 2 x G.SKILL Ripjaws X Series 4GB 240-Pin DDR3 1600 RAM

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• Why am I unable to mount my USB drive (unknown partition table)?

  - by Pat

  I'm a real newbie to linux. Anyway the problem is that my USB doesn't get recognized anymore which is really annoying because I need information from it. I've read like a zillion threads how to manually mount it but I really can't it to work. I hope it's just some easy, stupid problem where any of you could help me out quickly.. Here is the syslog: kernel: [ 6872.420125] usb 2-2: new high-speed USB device number 11 using ehci_hcd mtp-probe: checking bus 2, device 11: "/sys/devices/pci0000:00/0000:00:1d.7/usb2/2-2" kernel: [ 6872.556295] scsi8 : usb-storage 2-2:1.0 mtp-probe: bus: 2, device: 11 was not an MTP device kernel: [ 6873.558081] scsi 8:0:0:0: Direct-Access SanDisk Cruzer 8.01 PQ: 0 ANSI: 0 CCS kernel: [ 6873.559964] sd 8:0:0:0: Attached scsi generic sg3 type 0 kernel: [ 6873.562833] sd 8:0:0:0: [sdc] 15682559 512-byte logical blocks: (8.02 GB/7.47 GiB) kernel: [ 6873.564867] sd 8:0:0:0: [sdc] Write Protect is off kernel: [ 6873.564878] sd 8:0:0:0: [sdc] Mode Sense: 45 00 00 08 kernel: [ 6873.565485] sd 8:0:0:0: [sdc] No Caching mode page present kernel: [ 6873.565495] sd 8:0:0:0: [sdc] Assuming drive cache: write through kernel: [ 6873.568377] sd 8:0:0:0: [sdc] No Caching mode page present kernel: [ 6873.568387] sd 8:0:0:0: [sdc] Assuming drive cache: write through kernel: [ 6873.574330] sdc: unknown partition table kernel: [ 6873.576853] sd 8:0:0:0: [sdc] No Caching mode page present kernel: [ 6873.576863] sd 8:0:0:0: [sdc] Assuming drive cache: write through kernel: [ 6873.576871] sd 8:0:0:0: [sdc] Attached SCSI removable disk Thanks in advance

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• (Windows 7) Shared External Drive Permission Issues

  - by connec

  So, say I share my system (C) drive through windows (E.g. properties -> Sharing -> Advanced Sharing -> Share this Folder). I can then access this drive at \\Comp\C on another networked computer - all is well. However, if I insert a removable (USB) disk, say "E", and proceed to share it the same way, when I attempt to access \\Comp\E (either directly or through browsing) I get an error: Windows cannot access \\Comp\E You do not have permission to access \\Comp\E. Contact your network administrator to request access. Now, the permissions (Advanced Sharing -> Permissions) are set with "Everyone" having read access (same as the internal drive), so this doesn't make a lot of sense. Also of note, I have an SSH server on my computer (through Cygwin) and even through SSH (logging in as an administrator user) I cannot access /cygdrive/e (although /cygdrive/c is accessible). As a final note, the drive is of course accessible on the host machine (E:\), and also at \\Comp\E on the host machine.

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• haproxy + nginx: https trailing slashes redirected to http

  - by user1719907

  I have a setup where HTTP(S) traffic goes from HAProxy to nginx. HAProxy nginx HTTP -----> :80 ----> :9080 HTTPS ----> :443 ----> :9443 I'm having troubles with implicit redirects caused by trailing slashes going from https to http, like this: $ curl -k -I https://www.example.com/subdir HTTP/1.1 301 Moved Permanently Server: nginx/1.2.4 Date: Thu, 04 Oct 2012 12:52:39 GMT Content-Type: text/html Content-Length: 184 Location: http://www.example.com/subdir/ The reason obviously is HAProxy working as SSL unwrapper, and nginx sees only http requests. I've tried setting up the X-Forwarded-Proto to https on HAProxy config, but it does nothing. My nginx setup is as follows: server { listen 127.0.0.1:9443; server_name www.example.com; port_in_redirect off; root /var/www/example; index index.html index.htm; } And the relevant parts from HAProxy config: frontend https-in bind *:443 ssl crt /etc/example.pem prefer-server-ciphers default_backend nginxssl backend nginxssl balance roundrobin option forwardfor reqadd X-Forwarded-Proto:\ https server nginxssl1 127.0.0.1:9443

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• Uploading to another domain gives HTTP code 405

  - by dragon112

  I'm trying to upload a file (which can be quite large) from the website of one server to the backend of another server using plupload. Lets say: domain 1 = http://www.websitedomain.com/uploadform domain 2 = http://www.backenddomain.com/uploadhandler Trying to upload i send the following: OPTIONS /main/uploadnetwork.php HTTP/1.1 Host: backenddomain.com Connection: keep-alive Access-Control-Request-Method: POST Origin: http://www.websitedomain.com User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.79 Safari/537.4 Access-Control-Request-Headers: origin, content-type Accept: */* Referer: http://www.websitedomain.com/uploadform Accept-Encoding: gzip,deflate,sdch Accept-Language: nl-NL,nl;q=0.8,en-US;q=0.6,en;q=0.4 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 DNT: 1 But when I try to start the upload the server returns the following: HTTP/1.1 405 Method Not Allowed Allow: GET, HEAD, OPTIONS, TRACE Content-Type: text/html Server: Microsoft-IIS/7.5 X-Powered-By: ASP.NET X-Powered-By-Plesk: PleskWin Date: Mon, 01 Oct 2012 12:41:57 GMT Content-Length: 999 After doing some research I found out that a browser does this to check if the server will accept the intended message. It looks like my server doesn't feel like accepting a simple POST call even tho i use post all the time. The Google Chrome console gives the following error: XMLHttpRequest cannot load http://www.backenddomain.com/uploadhandler. Origin http://www.websitedomain.com is not allowed by Access-Control-Allow-Origin. Does anyone know how to stop the browser from checking or how i can tell my server to just accept the POST?

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• Subversion COPY/MOVE - File not found: transaction 'XXX-XX'

  - by theplatz

  I'm attempting to create a branch in one of my subversion repositories and keep running into an error. No mater what is done, I keep getting the following: File not found: transaction '3062-2e6', path '/Software/XXXXXX/branches/testbranch' I've noticed that the first part of the '3063-3e6' in the above message is the last successful committed revision in the repository. My apache logs don't give much more information: [Wed Nov 24 14:10:38 2010] [error] [client x.x.x.x] Could not MOVE/COPY /svn/p070361/!svn/bc/3049/Software/SXXXXXX/trunk. [404, #0] [Wed Nov 24 14:10:38 2010] [error] [client x.x.x.x] Unable to make a filesystem copy. [404, #160013] [Wed Nov 24 14:10:38 2010] [error] [client x.x.x.x] File not found: transaction '3059-2e2', path '/Software/XXXXXX/branches/testbranch' [404, #160013] This is all happening on a server with an nginx frontend that proxies to Apache for the subversion bits. Other repositories are able to branch fine and I was able to create the branch using file:/// from the command line on the server this is occurring on. The permissions on this repository match every other repository and disk space is not an issue.

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• Can anyone help me make my reverse proxy actually cache?

  - by Lenary

  Hi folks, I'm trying to configure a Reverse Caching Proxy but so far have had no luck. I would preferrably like to use apache (that will be all it will be used for), but am open to solutions using other software that can also run on Mac OS X 10.6 (I have also tried using Varnish and Squid, but with no more luck). We're running a system with about 80 mac mini clients that will be requesting lots of video from a server. To reduce load, we thought we could use Apache (which comes on the macs by default) to cache this video forever (or at least as long as possible) onto the macs' disks. I have managed to get a reverse proxy set up with apache using ProxyPass etc, but when i tried to add CacheEnable disk / to the configuration, nothing happened (i do have mod_disk_cache included). Can anyone help with my issue? The apache config file is here Thanks in advance Edit: So far I have been testing it with smaller text files, and it hasn't been caching properly. This suggests it is nothing to do with us actually downloading video, but actually to do with the cache configuration.

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• Replicated filesystem and EC2 MySQL

  - by El Yobo

  I'm currently investigating migrating our infrastructure over to run on Amazon's EC2 and am trying to figure out the best way to set up a MySQL service. I'm leaning towards running our own MySQL instances, rather than going with Amazon's RDS, but am still considering the best approach for performance and cost on the instance itself. In order to have persistent data, the MySQL data needs to be on an EBS volume (with some form of striped RAID, e.g. RAID0 or RAID10) to improve persistence. However, EBS IO is limited by the network interface (gigabit, so a theoretical maximum of 128 MB/s), while the ephemeral volumes have no such problem. I did see a suggestion for running two MySQL servers on an instance, with a master running on the ephemeral disk (which we would also RAID) and a slave storing changes to an EBS volume, but this has some additional overhead and complexity (two servers). What I was imagining is using some form of replicated file system such that I could have a filesystem on top of a RAID0 of ephemeral volumes to maximise performance all changes from the above immediately replicated to another RAID1 volume backed by multiple EBS volumes to ensure no data loss The advantages of this would be best possible IO performance for the DB server; no network delay in IO decreased IO on EBS volumes (as all read IO will be done on the ephemeral volumes) so decreased cost good data security, as it's backed onto redundant EBS volumes However, I haven't seen an appropriate system to replicate all changes from one volume to the other; is there a filesystem, or any other approach, which will do this? The distributed file systems, e.g. GlusterFS, DRBD etc seem to focus on replicating disks between servers, can they be set up to do what I'm interested in here? I also haven't seen anything about other's taking this approach. Do I have a solution in need of a problem here (i.e. is performance good enough, so this whole idea is redundant)? Is there some flaw in the plan?

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• after building in more ram, bios/debian does nothing [closed]

  - by derty

  My private server has 2x1gb Ram working with a 64bit Debian and an Q6600 Intel. This runs 2 virtual mashines on it each one recives 512mb RAM. Which you can immagine is a bit tight for the hole system. Now i got 2x2gb ram from a friend. I'm not sure if thery are clocking at the same speed, but i'm sure my power adaptor is not on his limit and can handle that. So there are 2 ram sockets left at the mainboard. I shuted down the system and build in the 4 gigs and looked what happen. After pressing the start button, everything gets noisy as known BUT the screen shows nothing, not even the bios stuff it usally does. Why isn't the system booting? I can immagine that it does not direkt link between booting debian and the bios not showing a thing. Or is it Grub? I mounted the system disk, and i can see it, switch folders write stuff with "vim" it does not seems like there is a problem.

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• File exists but is unreadable by PHP

  - by Aron

  More than once I have ran into this issue: I have a cache file that is automatically generated by PHP. It contains some generated PHP code. However for some reason the file cannot be read and parsed by PHP. These are the symptoms: File actually exists on file system. Using Terminal you can navigate to the file, view its contents (which are fully intact), etcetc. PHP file_exists() will report that the file exists...which is correct since it does :) Then I include() the file. But when actually parsing the file, PHP will just consider it an empty file. No fatal error, just no PHP code actually executed. Again, its as if the file was completely empty (which I assure you, it is not)... It is not a permissions issue. Permissions are set as needed. Workaround: open the file in Terminal via 'nano' or some other text editor and just save it to the disk again. After that (despite no changes to the content) PHP will run it just fine... As a clarification, I'd like to add that this happens rarely, but frequently enough to be a problem. And even when it does, there are hundreds of other similar files on the same system that work without a problem... If this were an issue affecting only my own scripts, I would consider that there must be a bug in the way I generate the PHP code. But no, the issue has occurred more than once when deploying to a server (usually from Beanstalk repository via FTP). The issue has been present on various servers, Debian and Ubuntu running Zend Community Server. Any ideas? One that crossed my mind was opcode cache-ing (part of Zend Server CE)...could it be that an empty version of the file is cached if it is requested while the write operation is still in progress?

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• Mysterious swap usage on EC2

  - by rusty

  We're in the middle of a project to move our infrastructure from a co-lo situation into Amazon EC2 and we've noticed some weird memory characteristics of the processes in our setup. Without going into too much detail about the specifics of our processes, we've noticed that on our EC2 instances "top" will show processes using a lot of swap space -- in fact, much greater than the amount of available swap or (if you add it all up) more than the available disk. Here's a sample top output: Mem: 7136868k total, 5272300k used, 1864568k free, 256876k buffers Swap: 1048572k total, 0k used, 1048572k free, 2526504k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ SWAP COMMAND 4121 jboss 20 0 5913m 603m 14m S 0.7 8.7 3:59.90 5.2g java 22730 root 20 0 2394m 4012 1976 S 2.0 0.1 4:20.57 2.3g PassengerHelper 20564 rails 20 0 2539m 220m 9828 S 0.3 3.2 0:23.58 2.3g java 1423 nscd 20 0 877m 1464 972 S 0.0 0.0 0:03.89 876m nscd You can see, for instance, that jboss is reportedly using 5.2 gigs of swap space which is definitely impossible since there's only 1G allocated and none is being used (probably because there's still 1.8G of RAM free). And here's the results of uname -a: Linux xxx.yyy.zzz 2.6.35.14-106.53.amzn1.x86_64 #1 SMP Fri Jan 6 16:20:10 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux We're running an AMI based off of the default Amazon Linux AMI (Amazon Linux AMI release 2011.09, so some RHEL5 and RHEL 6) with not too many customizations and definitely no kernel-level customizations. Something here tells me that on this particular kernel/distribution, the reporting of swap or maybe even total memory usage isn't what it appears to be... Any help would be appreciated!

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• How to fix a damaged/corrupted NTFS filesystem/partition without losing the data on it?

  - by Gareth

  I was going to install Fedora 15 along side my Windows 7 Starter on my Acer Apire One D255E and at some point during the resizing of the NTFS partition (the one with Windows on it) the setup failed. Now I cannot access this partition from any OS. When I tried to access it from a Fedora install running on a USB flashdrive I get this error: Error mounting: mount exited with exit code 12: Failed to read last sector (452534271): Invalid argument HINTS: Either the volume is a RAID/LDM but it wasn't setup yet, or it was not setup correctly (e.g. by not using mdadm --build ...), or a wrong device is tried to be mounted, or the partition table is corrupt (partition is smaller than NTFS), or the NTFS boot sector is corrupt (NTFS size is not valid). Failed to mount '/dev/sda5': Invalid argument The device '/dev/sda5' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around? It doesn't make a lot of sense to me but I was really hoping it would to someone and they can give me a way to restore the partition without losing everything on it (I have a lot of important notes from various classes on there)? Cheers.

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• After RAID failure SBS 2008 issues logging in and Exchange store does not mount

  - by Josh R

  today has been one of those days. Yesterday a hard drive in our Dell Poweredge 2900 server failed and the RAID array didn't degrade gracefully, so I called Dell (Server still under warranty) and got an engineer to work though the RAID issues with me. He was a nice guy but didn't do too much. We tried to put the RAID in a state where it was bootable and even though we only lost one disk there are still issues with the server. Once we got the server to boot there was an error message saying that the logonui.exe was corrupted and we needed to run chkdsk. I clicked through the error messages and the login screen never came up. So I power cycled the server and it chkdsk automatically but the login screen didn't appear. I tried safe mode, no difference there either. So the issues I am currently having are: 1) The server boots up, the loading windows screen comes up then it dumps me into a black screen where I can only see my mouse cursor. Ctrl+Esc doesn't work Ctrl+Alt+Del doesn't work 2) Some of the services come up: DHCP, DNS, DFS, and Print come up 3) The exchange information store and transport service don't start - I tried using mmc to connect to services.msc on the computer and start them but they throw an error message of "Can't start because group or dependency failed" Has anyone had a problem like this? Can anyone offer some guidance? Thanks a bunch!

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