/ - rtt - IT Resource

  • systemd management using systemctl and journalctl to check systemd logs


    systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system. The key commands or arguments you will use with systemctl are the following: Unit Commands:   list-units [PATTERN...]         List loaded units &nbs........
  • Linux Kernel USB Export Errors


    4.374647] usb_common: exports duplicate symbol usb_get_dr_mode (owned by kernel) [ 4.403334] usbcore: exports duplicate symbol __usb_get_extra_descriptor (owned by kernel) [ 4.427736] xhci_hcd 0000:00:15.0: xHCI Host Controller [ 4.427844] xhci_hcd 0000:00:15.0: new USB bus registered, assigned bus number 1 [ 4.429040] xhci_hcd 0000:00:15.0: hcc params 0x200077c1 hci version 0x100 quirks 0x01109810 [ 4.429141] xhci_hcd 0000:00:15.0: cache line size of 64 is not sup........
  • hwloc-nox set CPU affinity in Linux


    sudo apt-get install  hwloc-nox Reading package lists... Done Building dependency tree       Reading state information... Done The following NEW packages will be installed:   hwloc-nox 0 upgraded, 1 newly installed, 0 to remove and 530 not upgraded. Need to get 151 kB of archives. After this operation, 453 kB of additional disk space will be used. Get:1 http://archive.ubuntu.com/ubunt........
  • Cannot install moodle


    After starting the install it stalls here: admin/index.php?cache=0&agreelicense=1&confirmrelease=1&lang=en If you manually refresh you get a Plugins check screen: Installation System Moodle second step fails just blank screen: https://domain.la/user/editadvanced.php?id=2 Solution: give up and choose something else it shouldn't be thi........
  • Debian Mint Ubuntu compiling xmr-stak


    sudo apt-get install libcurl4-openssl-dev git build-essential autotools-dev autoconf libcurl3 sudo apt-get install libcurl4-gnutls-dev git clone https://github.com/wolf9466/cpuminer-multi sudo apt-get install cmake  libpthread-* libmicrohttpd-dev libssl-dev libhwloc-dev git clone https://github.com/fireice-uk/xmr-stak-cpu.git make install cd bin chmod +x xmr-stak-cpu ./xmr-stak -O xmr........
  • migration/4 migration 4 is using too much CPU


    top - 13:02:52 up 603 days, 19:19,  2 users,  load average: 5.01, 4.15, 3.44 Tasks: 604 total,   5 running, 599 sleeping,   0 stopped,   0 zombie Cpu(s): 17.7%us, 36.1%sy,  0.0%ni, 42.0%id,  4.1%wa,  0.0%hi,  0.2%si,  0.0%st Mem:  16278908k total,  4269684k used, 12009224k free,   119672k buffers Swap:        8k total,    ........
  • Centos 7 - How To Install NFS and Mount Remotely


    1.) First install nfs-utils [root@bcitcourse ~]# yum -y install nfs-utils Loaded plugins: fastestmirror base                                                         &n........
  • Linux How To Free Wasted Memory RAM in Buffers


    We all know Linux is known for good memory management but is it really?  It seems all on its own with hardly anything running that you can come back in days or weeks and find that almost all of your RAM is used! And many will say "no don't worry it's buffers for optimization" but it doesn't seem to help because what is in buffers is not available to use for new programs running or ones that allocate more RAM as far as I can tell. The reason I know........
  • PHP Warning: Cannot load module 'XCache' because conflicting module 'apc' is already loaded in Unknown on line 0


    PHP Warning:  Cannot load module 'XCache' because conflicting module 'apc' is already loaded in Unknown on line 0 Solution: yum remove php-pecl-apc-*........
  • Unable to load dynamic library '/usr/lib64/php/modules/module.so' - /usr/lib64/php/modules/module.so: cannot open shared object file: No such file or directory in Unknown on line 0


    Getting this error on Centos 6 with PHP 5.3 when just running "php -v"   PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/module.so' - /usr/lib64/php/modules/module.so: cannot open shared object file: No such file or directory in Unknown on line 0 PHP Warning:  Cannot load module 'XCache' because conflicting module 'apc' is already loaded in Unknown on line 0 Solution:........
  • M2Crypto.SSL.Checker.WrongHost: Peer certificate subjectAltName does not match host, expected fedora-archive.ip-connect.vn.ua, got DNS:mirror.ip-connect.vn.ua


    You are using Centos 5 which is deprecated so nothing in yum will work until you follow this post to use the vault: http://realtechtalk.com/Centos_59_Working_Vault_Repo_file-1921-articles yum update Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile  * epel: fedora-archive.ip-connect.vn.ua Traceback........
  • Centos 5.9 Working Vault Repo file


    Centos 5 is not supported running yum will produce an error like this: YumRepo Error: All mirror URLs are not using ftp, http[s] or file.  Eg. Invalid release/ removing mirrorlist with no valid mirrors: /var/cache/yum/base/mirrorlist.txt Error: Cannot find a valid baseurl for repo: base Solution - Update this file CentOS-Base.repo   # CentOS-Base.repo........
  • Linux Mint/Ubuntu/Debian apt how to downgrade a package


    First of all check to see which version if any you have available for a downgrade: apt-cache showpkg packagename Downgrade/Install old package: apt-get install package=version Example apt-cache showpkg caja Package: caja Versions: 1.10.3-1+rafaela (/var/lib/apt/lists/packages.linuxmint.com_dists_rafaela_import_binary-amd64_Packages) (/var/........
  • ffmpeg Linux Mint download, compile and install howto


    #if you have nvidia make sure you install the nvidia-cuda-toolkit so hardware acceleration can be used wget http://ffmpeg.org/releases/ffmpeg-3.3.2.tar.bz2 tar -jxvf ffmpeg-3.3.2.tar.bz2 cd  ffmpeg-3.3.2/ ./configure --disable-yasm install prefix            /usr/local source path              ........
  • USB 3.0 External HDD Enclosure Seagate UAS problems - [sdd] tag#1 CDB: Write(16) 8a 00 00 00 00 01 70 04 08 68 00 00 00 08 00 00


      This is a 8TB Seagate external USB 3.0 device apparently newer kernels use a module called "UAS" instead of "USB Storage" which causes issues as a lot of devices are not properly supported in UAS mode by the kernel driver.  The solution some say is to disable UAS specifically for your USB device but I'd rather just disable UAS altogether.   Solution blacklist UAS: *do not do this it does not work and just causes your USB 3.0........
  • cudaminer freezes Linux Mint taints kernel


    When running cudaminer once it tries to initialize the card the entire screen freezes.  The computer itself is still running but the Xorg is done for, you cannot even switch to another console window and must reboot (even an mdm or Xorg restart does not help). At first cudaminer will give you these errors: stratrum_recv_line failed ...retry after 15 seconds GPU #0: Geforce 210 with compute ca........
  • USB Device/MP3 Player not working properly and can't browse the device filesystem? Check the cable twice and again!


    Here is a simple MP3 player and now there's a reason to understand why the supplied cable has some kind of capacitor and is very short.  These devices can be VERY finicky and any voltage fluctuation or difference is enough to cause issues.   Take for example the error messages from Linux Mint: [804829.895414] usb 1-1: USB disconnect, device number 11 [806961.109030] usb 1-1: new high-speed USB device number 12 using xhci_hcd........
  • Track 01: 34 of 1726 MB written (fifo 100%) [buf 99%] 3.6x.Errno: 5 (Input/output error), write_g1 scsi sendcmd: cmd timeout after 1.897 (40) s CDB: 2A 00 00 00 44 A9 00 00 1F 00 resid: 6144 cmd finished after 1.897s timeout 40s write track da


    These errors believe it or not are simply because of not being the root user or running with sudo! However if you didn't know to try as root you'd think there was a problem with your burner or disc  Essentially it looks like without root you cannot send the required scsi commands to continue writing.  I think cdrecord should have built-in tests or safeguards to see if it has the permissions to run the required commands. I guess for more advanced users the idea is simila........
  • xdebug easiest howto get going


    Just make sure you have php-xdebug installed and edit your php.ini: [xdebug] xdebug.profiler_enable = 0 xdebug.profiler_enable_trigger = 1 xdebug.profiler_output_dir = "/tmp/xdebug/" xdebug.output_name = "cachegrind.out.%t-%s" Also make and set permissions on /tmp/xdebug: mkdir /tmp/xdebug chmod 777 /tmp/xdeb........
  • phpBB3 slow and internal dummy connection


    Using Apache 2.2 and PHP 5.6 PHPBB3 is very slow to respond.  Actually for some reason it takes so long to even register a log entry in access_log as in several seconds or a few minutes later it shows up in Apache.  All other vhosts and Apache access stops working and freezes until the request to access PHPBB3 slowly completes. It seems to randomly be slow if you stop using it whether for posting or reading the forums.  I've migrated to different machines including........
  • What happens when you unplug 1 or more devices from an mdadm RAID array to simulate a failure in Linux Ubuntu/Centos/Debian?


    In short the two drives in the array were /dev/sdd and /dev/sde.  The kernel sees they were unplugged and have gone down as you can see below. mdadm caught the first one being unplugged /dev/sde and disabled the missing drive.  However when the final drive that was part of the array is unplugged it didn't notice at all.  Instead it complains about an IO error later for drives that the kernel knows do not exist anymore. [45817.162728] ata4: exception........
  • Using a proxy with yum in Centos 6


    Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os error was 12: Timeout on http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os: (28, 'Operation too slow. Less than 1 bytes/sec transfered the last 30 seconds') Error: Cannot find a valid baseurl for repo: base You would think this should be fine and simple like using a proxy with most other software? However........
  • PYCURL ERROR 22 - The requested URL returned error: 404 Not Found Solution


    # yum -y install qemu-kvm Loaded plugins: fastestmirror Setting up Install Process Loading mirror speeds from cached hostfile  * base: mirror.lzu.edu.cn  * elrepo: ftp.utexas.edu  * epel: ftp.jaist.ac.jp  * extras: mirrors.aliyun.com  * openvz-kernel-rhel6: mirror.fdcservers.net  * openvz-utils: mirror.fdcservers.net  * updates: mirrors.nwsuaf.edu.cn Resolving Dependencies........
  • ADATA SU800 256GB 3D NAND Flash SSD Test & Review


    I keep reading these drives are slower, but they are cheap and still SSD and work very fast for my needs. As you can see the sequential read is 481-491MB/s, if I put them in MDADM RAID10 mode (normal RAID1) they should give me well over 900MB/s and with redundancy and being very cheap for what they offer. [1232206.315622] scsi 8:0:1:0: Direct-Access     ATA      ADATA SU800   &........
  • OpenVZ Migration Hostnode Containers from Centos 5 to Centos 6


    migrating from an old OpenVZ (Centos 5) to new OpenVZ (Centos 6) Also if migrating from 32-bit HN to 64-bit your RAM will probably be much bigger than it should be! 16x bigger eg. 32bit HN:              total       used       free     shared    buffers     cached Mem:&nb........
  • blocked for more than 120 seconds issues with iowait and timeout on Live Linux distribution while writing to physical disk


    This happened while an mdadm array was syncing, all access from writing a new blank file to opening a small .txt file was very slow:   [222117.312078] kjournald starting.  Commit interval 5 seconds [222117.685060] EXT3-fs (md0): using internal journal [222117.685096] EXT3-fs (md0): mounted filesystem with ordered data mode [222122.376847] kjournald starting.  Commit interval 5 seconds [222122.602825] EXT3-fs (md2): using internal jour........
  • HTML files in Apache still displaying as raw text even with DefaultType, ForceType etc.


    There was only one solution here and it was the following: edit /etc/httpd/conf/httpd.conf Comment the lines for the Mime Magic Module: #   MIMEMagicFile /usr/share/magic.mime #    MIMEMagicFile conf/magic   *Don't forget to restart Apache and clear your browser cache twice I was using DefaultType and ForceType a........
  • Cannot Read License File cPanel Solution


    This can happen because port 80 is not open, or your license has expired and/or your IP is out of date and also if the license server itself from cPanel is having issues. In most cases as long as you have a valid license the following command will solve it:  /usr/local/cpanel/cpkeyclt Updating cPanel license...Done. Update succeeded. Building global cache for cpanel...Done   Cannot........
  • Cannot load /etc/httpd/modules/mod_file_cache.so into server: /etc/httpd/modules/mod_file_cache.so:


    Stopping httpd:                                            [FAILED] Starting httpd: httpd: Syntax error on line 73 of /etc/httpd/conf/httpd.conf: Cannot load /etc/httpd/modules/mod_file_cache.so into server: /etc/httpd/modules/mod_file_cache.so: cannot open shared obje........
  • Apache SSL Reverse Proxy Very Slow Solution


    This is a simple fix but not a simple problem and it still doesn't make sense to me. But in a nutshell if your target proxy server works fast when accessing directly over SSL then this may be your issue. It seems SSL does not play nicely when the target proxy destination/host has a riduculously long key (such as 8192 bits long).  Now this is normally not a problem, in fact the target server could be accessed with hardly any delay directly despite such a long key.........
  • Linksys E2500 DD-WRT Upgrade Instructions and Enabling 5ghz with Tomato Firmware


    1.) Flash directly to this file: http://tomato.groov.pl/download/K26RT-N/build5x-132-EN/Linksys%20E-series/tomato-E2500-NVRAM60K-1.28.RT-N5x-MIPSR2-132-Max.zip *I was never able to get the larger "Mega" file to work, at least not initially so I recommend the file above. To enable 5ghz I had to do the "Clear NVRAM" Option before it was shown. 2.) Or if you don't need 5ghz (most devices do not support it and cannot........
  • unfortunately lg keyboard has stopped - LG Phone Keyboard Issue


    This seems to effect many other LG phones , specifically their keyboard app and basically makes your phone unusable where you cannot use the keyboard because that message keeps popping up and the keyboard will not load. unfortunately lg keyboard has stopped solution: 1. Go to your settings and manage apps and find the LG Keyboard app: 2. Stop it from running, delete all data and clear all cache. After the above you will probably find that your........
  • Installing zoneminder on Ubuntu/Debian Linux Howto


    sudo apt-get install zoneminder [sudo] password for one: Reading package lists... Done Building dependency tree       Reading state information... Done The following packages were automatically installed and are no longer required:   libuser-perl python-evince kdebase-apps kwrite unixodbc   libgnomeprint2.2-data python-soappy vgabios python-metacity hddtemp   python-mediaprof........
  • Centos yum mirror problem error "[Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found""


    [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found" The above happened when for some reason all the mirrors in my cache didn't have the files (some mirrors only keep the latest version of Centos). I tried to block them all but that didn't help because it seemed the mirrors were all hardcoded no matter what I tried. Here is how to fix it and reset your mirror list in Centos cd /var/cac........
  • ECC Errors in action


    Message from syslogd@server at Sep 14 11:35:59 ...  kernel:[Hardware Error]: MC4 Error (node 1): DRAM ECC error detected on the NB. Message from syslogd@server at Sep 14 11:35:59 ...  kernel:[Hardware Error]: Error Status: Corrected error, no action required. Message from syslogd@server at Sep 14 11:35:59 ...  kernel:[Hardware Error]: CPU:6 (10:8:0) MC4_STATUS[Over|CE|MiscV|-|AddrV|CECC]: 0xdc00400021080813........
  • Lost connection to MySQL server during query [2013]


    This happened while trying to delete several thousand users from phpBB and basically corrupted the innoDB tables. InnoDB: Page lsn 3 881164362, low 4 bytes of lsn at page end 881164362 InnoDB: Page number (if stored to page already) 86920, InnoDB: space id (if created with >= MySQL-4.1.1 and stored already) 0 InnoDB: Page may be an index page where index id is 700 InnoDB: (index "tid_post_time" of table "phpBBdb2005"."phpbb3_p........
  • yum error "Error: database disk image is malformed" solution


    yum -y install mathtools Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile  * base: centos.mirror.rafal.ca  * epel: mirror.steadfast.net  * extras: mirror.agmn.ca  * rpmforge: repoforge.mirror.constant.com  * updates: centosb5.centos.org extras                         ........
  • OpenVZ mismatched kernel and dev when compiling.


    ./configure ./configure: line 91: cd: /lib/modules/2.6.32-042stab084.25/build: No such file or directory Error: kernel version not found. Please make sure your kernel is configured. dr-xr-xr-x.  4 root root   4096 Feb 21 06:13 .. lrwxrwxrwx   1 root root     45 Feb 21 06:13 build -> ../../../usr/src/kernels/2.6.32-042stab084.25 drwxr-xr-x   2 root root   4096 Feb 12 20........
  • yum Centos 386 and 64 bit conflict resolution


    This can happen when you install RPMForge or other repos with the wrong architecture and here's how you fix it (simply uninstalling won't usually fix it): solution yum clean all yum -y install openvpn Loaded plugins: fastestmirror, presto Loading mirror speeds from cached hostfile  * base: mirror.its.sfu.ca  * extras: centos.mirror.nexicom.net  * rpmforge: mirror.cpsc.ucalgary.ca  * up........
  • yum error installing php solution - exclude php from being installed from third party repos


    Error: Package: php-Monolog-dynamo-1.7.0-1.el6.noarch (epel)            Requires: php-aws-sdk Error: php-pecl-zendopcache conflicts with 1:php-eaccelerator-0.9.6.1-1.el6.x86_64 Error: php-xcache conflicts with php-pecl-apc-3.1.9-2.el6.x86_64 Error: php-pecl-zendopcache conflicts with php-pecl-apc-3.1.9-2.el6.x86_64 Error: Package: php-horde-Horde-Vfs-2.1.2-2.el6.noarch (epel)    &n........
  • Centos Howto Upgrade to PHP 5.3 from 5.2


    It's not as simple as "yum install" as you can see below and it doesn't stop there.  yum install php53 Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile  * rpmforge: mirror.us.leaseweb.net  * extras: centos.mirror.rafal.ca  * updates: centos.mirror.nexicom.net  * base: centos.mirror.nexicom.net  * addons: centos.mirror.nexicom.net Setting up Install Process........
  • What a hdd hard drive and mdadm RAID array failure looks like in Linux


    [3805108.257042] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB) [3805108.257052] sd 0:0:0:0: [sda] Write Protect is off [3805108.257054] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [3805108.257066] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [3805108.257083] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB) [3805108.257090] sd 0:0:0:0: [sda] Write Protect is off........
  • [Hardware Error]: CPU:0 MC4_STATUS[-|CE|MiscV|-|AddrV|CECC]: 0x9c054c84011c011b [Hardware Error]: cache level: L3/GEN, tx: GEN, mem-tx: RD [Hardware Error]: Northbridge Error (node 0): L3 data cache ECC error.


    This server has been running for weeks without issue, it's currently only using 1 of 2 CPUs as it is running in the office as a test bed (mainly due to the handle 12 bay storage/great for testing HDDs).  The errors below seem to mainly be from AMD CPUs, it's only happened a single time and in the days since I got that error it hasn't occurrred. Interestingly enough /proc/cpuinfo still shows all 4 cores of the CPU (Opteron 2373 Quadcore HE) and the functionality doesn't seem........
  • Openvz OOM Centos Issue Memory Config Settings Solution


    Linux box13. 2.6.32-042stab076.5 #1 SMP Mon Mar 18 20:41:34 MSK 2013 x86_64 x86_64 x86_64 GNU/Linux even setting privvmpages to a specific setting DOES not affect "free -m" in containers. This is probably a kernel issue  23:36:29 up 159 days,  7:12,  4 users,  load average: 0.42, 0.44, 0.33 [root@box13 ~]# free -m              total  &n........
  • CPanel suhosin install failed


    /scripts/phpextensionmgr install PHPSuHosin Updating md5sum list Fetching http://httpupdate.cpanel.net/cpanelsync/easy/targz.yaml (connected:0).......(request attempt 1/12)...Resolving httpupdate.cpanel.net...(resolve attempt 1/65)...     Fetching http://httpupdate.cpanel.net/mirror_addr_list (connected:0).......(request attempt 1/3)......connecting to 74.50.120.123...@74.50.120.123......connected......receiving...100%......request success......Done........
  • Dell FS12-NV7 2U Server Information and Guide


    I've got one of these for testing projects from work at home and got more than I bargained for with the time I've spent on it due to the storage handing/Perc 6/i cards. My particular model came with the following: 2U Rack Mount Server with Rails 2xOpteron 2373 EE (Quad Core, there is a 6-core version that can be found at times) 16GB RAM 2 x 250GB Seagate SATA 2 x Dell Perc 6/i (horrible and a nightmare to work........
  • Dell Perc 6/i cannot downgrade


    I flashed an LSI Logic firmware to it and it broke the BIOS (cannot do Ctrl+R) for booting purposes but allows other functionality to work normally. I tried downgrading to a Dell firmware for Perc 6i but it won't work, not even with MegaCli wget http://downloads.dell.com/FOLDER00416606M/1/SAS-RAID_Firmware_W83M2_LN32_6.3.1-0003_A14.BIN --2013-08-26 12:53:39--  http://downloads.dell.com/FOLDER00416606M/1/SAS-RAID_Firmware_W83M2_LN32_6.3.1-0003_A14.BIN Resolvi........
  • LSI MegaRAID Adventures, Guide and HowTo


    LSi Megaraid At first it was configured as a RAID 0, then I deleted the Virtual Disk Group. I thought both drives would be shown and detected in Linux as sda and sdb but it actually shows nothing. To make them work you have to hit Ctrl+R before the system boots (when prompted) and create a Virtual Disk Group.  In my case I created each one as RAID 0 (with a single drive only) as I just wanted JBOD but there is no such option or default in these Dell Pe........
  • pxe-32 tftp open timeout


    pxe-32 tftp open timeout   The solution was to enable tftp in xinetd with "chkconfig tftp on". See the troubleshooting below:   chkconfig --list NetworkManager     0:off    1:off    2:off    3:off    4:off    5:off    6:off acpid              0:off&n........
  • WD 20EARX Dead Again


    Another new drive bad from the start:   Jun  2 15:14:18 one-desktop kernel: [15895.386779] ata2.00: exception Emask 0x50 SAct 0x1 SErr 0x280900 action 0x6 frozen Jun  2 15:14:18 one-desktop kernel: [15895.386782] ata2.00: irq_stat 0x08000000, interface fatal error Jun  2 15:14:18 one-desktop kernel: [15895.386784] ata2: SError: { UnrecovData HostInt 10B8B BadCRC } Jun  2 15:14:18 one-desktop kernel: [15895.386788] ata2.00: cmd 60/0........
  • Directadmin error/** Found 7 pre-existing rpmdb problem(s), 'yum check' output follows: e2fsprogs-devel-1.41.12-3.el6.i686 has missing requires of e2fsprogs-libs = ('0', '1.41.12', '3.el6') e2fsprogs-devel-1.41.12-3.el6.i686 has missing requires of l


    Solution To The Following: yum -y install zlib-devel yum -y install e2fsprogs* *** Cannot find /usr/include/et/com_err.h.  (yum install libcom_err-devel) *** Installation didn't pass, halting install. Once requirements are met, run the following to continue the install:   cd /usr/local/directadmin/scripts   ./install.sh Common pre-install commands:  http://help.directadmin.com/it........
  • kvm cannot boot xen guest using lvm


    This booting error is because the Xen PV guest image uses the Xen kernel, this is not compatible with anything but a host running a Xen kernel. I did a kpartx -av virtual.img and then it created some partitions that showed up in fdisk. I mounted it and did a chroot into it and removed the xen kernel and installed a normal kernel but Xen still shows the same kernel in Grub (only the Xen one). This is strange but it seems like this Xen PV guest has some sort of hidden or........
  • Delete arp entry from Linux Howto


    arp -a syst (192.168.1.122) at 21:96:43:3a:62:a2 [ether] on eth0 arp -d 192.168.1.122 If you get an error do: arp -d 192.168.1.122 -i eth0 Sometimes the arp cache just won't clear either, some say it should automatically but there are cases where the above doesn't work.  I believe it may be that some network applications are keeping the entry alive but this is just a guess.........
  • Howto Copy/Backup/Restore All Firefox Settings/Preferences/Addons/Bookmarks to another computer/desktop


    I've used rsync again for this because I found it very simple, I've only excluded the Cache directory since it's not necessary and could be several GB in size. rsync -Phaz --exclude=Cache/* user@remotehost.com:/home/user/.mozilla/firefox/profile.default/* /home/user/.mozilla/firefox/ec1n9opl.default/ This is a great way once again to get going how you were on the old/remote computer fairly quickly.  It even restores all of your history in........
  • Thunderbird How-To Copy/Backup/Restore Accounts and Settings to Another Computer


    The best way is to use rsync, I've set it up so it doesn't copy unnecessary files, or at least ones I'm sure aren't needed. Here is the rsync command I used (adapt to your specific Thunderbird profile location): rsync -hazv user@remotehost.com:/home/user/.thunderbird/sbrer.default/* /home/user/.thunderbird/4nyb0.default/ --exclude=global* --exclude=Cache --exclude=ImapMail --exclude=Mail This is a great way to get your e-mail accounts going on a new c........
  • Centos how to upgrade from PHP 5.2 to 5.3 without downtime


    This may sound silly but there will be conflicts/issues with the default Centos repository so you have to use a third party like remi (I prefer not to do this but it's the only option unless you migrate your sites/data to another server or can stand some downtime-not an option IMHO on a production server). You may need to upgrade to PHP 5.3 to run Joomla or many other reasons. Your host needs to use PHP 5.2.4 or higher to run this version of Jo........
  • Ubuntu 10 Nvidia Drivers Not Updated After Kernel Update Solution/How-To Manually Rebuild nvidia kernel modules for Ubuntu


    I dread updating the kernel and rebooting to find the Ubuntu graphics aren't working and you have to manually intervene.   This is usually because Ubuntu for whatever reason didn't update the drivers you need (eg. the manually compiled Nvidia Kernel driver that MUST be recompiled for each and every kernel update unfortunately). The most common reason may be that "linux-source" hasn't been installed automatically on my system.  I tried to manually reinstall the........
  • Linux Kernel Panic Messages - Symptoms of bad RAM module/stick


    These were caused by a bad stick of Corsair RAM [<c0466769>] free_hot_cold_page+0xfc/0x150 [<c04667d1>] __pagevec_free+0x14/0x1a [<c0468c6b>] release_pages+0x127/0x12f [<c04692d1>] __pagevec_release+0x15/0x1d [<c04697db>] __invalid_mapping_pages+0x120/0x156 [<c046981........
  • Linux Out of Memory OOM Object Killer Solution "Out of memory: kill process 1955 (sshd) score 81 or a child"


    I had a system running a 128MB live CD image with 2.8 gigs of available RAM and the OOM kernel killer went crazy when using dd for more than 8 minutes and kept killing everything.  I've read that this is due to a low-memory issue and paging in the kernel and 32-bit systems with lots of RAM. I even enabled swapspace on my LiveCD and the issue happened 25 minutes into dd rather than 8 minutes, so what gives? Also no swap space was ever used! cat /proc/s........
  • How To Test If Your Hard Drive Is Good/Signs of dying hard drive


    I like dd, although it only reads it, usually a read test of the entire disk will uncover if your hard drive is bad in some parts.  This is a good thing to do at least once a month, a lot of times bizarre program behavior, laginess and crashing/unnmounting problems etc.. are due to a failing disc and SMART won't know it or indicate a problem: We must also remember there's never a guarantee, I've found that ever since we moved to larger and more platters per drive with 1TB drives........
  • Openvz YUM Error Solution to "[Errno -1] Metadata file does not match checksum Trying other mirror."


    It's weird because I have a nearly identical box and setup and I can update the ovzkernel-PAE* just fine but on this box it doesn't work. I only get this error with the openvz.repo and not others such as Centos-Base.repo With my other server it works normally: ================ Setting up Update Process Resolving Dependencies --> Running transaction check ---> Package ovzkernel-PAE.i686 0:2.6.18-238.12.1.el5.0........
  • Kernel/make compilation time and how to improve compile times/compile the Linux kernel faster without hardware upgrades


    I thought only a faster CPU and SSD would help but I already have a Quad-Core CPU and it wasn't being maxed out.  The actual tests were performed on an AMD-V enabled 128MB dual core VMWare container though. There is a flag that can be passed to make in order to start multiple threads, by specifying 4 threads I was able to reduce the whole kernel compilation time from scratch by about 50%! (65minutes vs 31minutes!).  *Yes I did do a make clean before each co........
  • List of Free Public DNS Servers IP Addresses


    One thing to note about DNS servers and providers is that they aren't always trustworthy, not even if they're Google or your favorite ISP.  Any DNS server can compromise your privacy, and they are likely tracking your browsing habits and keeping logs of it.  Sometimes it's for Marketing/Research purposes such as Google's GMail service which they admit is scraped/datamined.  I would expect nothing less from their DNS service. The other danger with such widely used and pu........
  • mysql enable slow query logging/Query Cache Solution - find/track cause of slow mysqld/high IO/CPU usage


    If you have a webserver and find you have high IO/lagginess MySQL is one of the first things to check.  It turns out MySQL was my problem and it was creating a high load on my server, especially for IO. How to Enable MySQL Slow Query Logging To Find Slow Performance/Queries vi /etc/my.cnf Add this anywhere under [mysqld] #slow queries log-slow-queries = /var/log/mysql/mysqlslowqueries.log long_query_time = 1........
  • Apache High CPU Usage Enable Mod_Status Guide Solution - Find Cause of High CPU Usage Script/Domain


    mod_status is a great way to track down the source of high CPU usage and to find what vhost/script is the cause of it. It gives you a live view of bandwith usage, CPU usage, and memory usage broken down by domain/vhost and script/URI. Enable mod_status vi /etc/httpd/conf/httpd.conf ExtendedStatus On <Location /server-status> SetHandler server-status Order Deny,Allow Deny from all All........
  • vnstat setup guide/tutorial


    yum -y install vnstat chown nobody.nobody -R /var/lib/vnstat/ #replace venet0 below with your desired interface sudo -u nobody vnstat -u -i venet0 #edit: vi /etc/sysconfig/vnstat #VNSTAT_OPTIONS="-i venet0" # only use the sed below if you are using venet0 instead of eth0 or replace accordingly sed -i 's/eth0/venet0/g' /etc/sysconfig/vnstat   [root@monitor]# yum install vn........
  • Are my WDEARS20 Drives dying already?


    This happened during a RAID array check: SMART says both drives pass the test, but I'm doing a long test on them and hopefully this is not a hardware error. Apr  3 04:22:01 remote kernel: md: syncing RAID array md2 Apr  3 04:22:01 remote kernel: md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc. Apr  3 04:22:01 remote kernel: md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reconstruction. Apr........
  • 2011 Best Laptop - HP 15.6" Laptop featuring AMD Athlon II P340 Processor (G62-420CA)


    My mother needed a new laptop and I recommended her the same one I would have bought myself or my wife, that means the cheapest possible laptop with the most features for the money. This HP shines at this price point and one thing that made me stay away from buying more and recommending HP/Compaq was the poor battery life.  Not anymore, this model has an industry leading up to 4 hours of battery life. Key Factors for Choosing It: HDMI Out........
  • Yahoo Mail (email) DNS Server Out Of Date Problems


    I don't expect this to be solved soon but some of Yahoo's DNS servers are out of whack.  I changed the IPs of some nameservers of some domains and now most Yahoo users can't e-mail to those domains! As you can see below by the "No MX or A records for mychangedomain.com", now Yahoo's DNS/mailserver DNS cache is wrong.  You would think they would at least have cached the old incorrect records, but instead for some reason their DNS cache has no entry and doesn't seem........
  • Ubuntu 9.04 Crash


    CPU/Kernel/MB/RAID problem? Jan  5 12:45:05 testbox kernel: [653298.890004] BUG: soft lockup - CPU#0 stuck for 61s! [hal-acl-tool:4168] Jan  5 12:45:05 testbox kernel: [653298.890005] Modules linked in: vmnet vmci vmmon binfmt_misc drbd video output input_polldev ocfs2_stackglue ocfs2_dlmfs ocfs2_dlm ocfs2_nodemanager configfs k8temp hwmon_vid lp snd_hda_intel snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi........
  • Dying Seagate 7200.11 SD15


    [137392.910057] ata4.00: exception Emask 0x0 SAct 0x1 SErr 0x80000 action 0x6 frozen [137392.910077] ata4: SError: { 10B8B } [137392.910095] ata4.00: cmd 60/20:00:00:00:00/00:00:00:00:00/40 tag 0 ncq 16384 in [137392.910099]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout) [137392.910122] ata4.00: status: { DRDY } [137392.910135] ata4: hard resetting link [137393.440060] ata4: SATA link........
  • yum in Centos 5/Xen halts and exits suddenly


    yum exits in the middle The problem is this VPS seems to be an OpenVZ template from HyperVM.  The only way to make it work was to disable i386 packages since this was an x64 kernel.  That shouldn't be necessary but it was the only way to make yum stop quitting after the first package or two.  I couldn't find any issue by checking the logs either. echo y|yum install vim-minimal telnet expect jwhois net-tools slocate iptables elinks gawk L........
  • mdadm RAID 1 adventures


    I separated the 2 drives in the RAID 1 array. 1 is the old one /dev/sda and is out of date, while the separated other one /dev/sdc was in another drive and mounted and used with more data (updated). I wonder how mdadm will handle this: usb-storage: device scan complete md: md127 stopped. md: bind<sda3> md: md127: raid array is not clean -- starting background reconstruction raid1: raid set md127 active with 1 out of 2 m........
  • mdadm when a RAID 1 member dies


    [27969.398749] sd 5:0:0:0: [sdb] 3907029168 512-byte hardware sectors (2000399 MB) [27969.398749] sd 5:0:0:0: [sdb] Write Protect is off [27969.398749] sd 5:0:0:0: [sdb] Mode Sense: 00 3a 00 00 [27969.398749] sd 5:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [27972.117543] ata6.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x0 [27972.117543] ata6.00: irq_stat 0x48000000 [27972.117543] ata6.00: cmd 60/08:00:ff:7........
  • Realtek r8169 1gbit/1000mbit NIC/Ethernet Goes Down/Halts on Large File Transfer/Heavy Network Usage


    This is obviously a bug in the r8169 kernel module and it seems to affect a lot of people.  I upgraded to the latest kernel and hope this won't happen anymore, as it is a very serious error.  This is especially serious for those who are running servers with this chipset, who can afford for the NIC to randomly go off-line for no apparent reason?   [655548.189113] type=1505 audit(1277067560.902:5): operation="profile_load" name="/usr/bin/freshclam&q........
  • FUSE/Curlftpfs mount ftp account as drive partition in Linux


    This is a great way to use your ftp server space, for example on your web hosting account (although I believe many hosts don't allow storage like this), but if you have a VPS/Dedicated Server etc.., this would be perfect.  Imagine how easy it is to work with an ftp account that you can just mount as a normal partition or directory in Linux, it would be great for backups etc..   Name curlftpfs - mount a ftp host as a local directory Synopsis........
  • Compile PHP 5.3.2 on Centos 5 and CPanel/WHM because of error - Fatal error: Call to > undefined function imagecreatefromjpeg()


    This function and others may not work with the stock PHP install on Centos/CPanel:  Fatal error:  Call to > undefined function imagecreatefromjpeg() Even with libjpeg-devel installed it won't work because PHP was not compiled with jpeg support, so we have to do the dirty work ourselves :) Here is the command/yum's I did to install missing libraries for PHP that configure will complain about (yes it is a one by one process). yum install bzip2-........
  • Unixbench Score on Core i5 750 with OpenVZ Kernel vs Xen/Openvz


    This was unbelievable how much the Xen kernel slows things down, keep in mind both tests were done on the hostnode, one was with the Openvz-Xen hybrid kernel and the other was just OpenVZ.  You can see the performance difference is nearly 300% better when not using the Xen kernel. OpenVZ-Xen Kernel Test Results (I was wondering what was wrong/so slow with my Core i5!)    #    #  #    #  #  #  &n........
  • rsync halted froze Out of memory: kill process 7559 (rsync) score 635 or a child Killed process 7559 (rsync)


    Out of memory: kill process 7559 (rsync) score 635 or a child Killed process 7559 (rsync) I was surprised to see this in my dmesg when my rsync backup suddenly stalled/stopped. This system has 3 gigs of RAM and lots of free memory so I don't understand what is happening.   rsync invoked oom-killer: gfp_mask=0x200d2, order=0, oomkilladj=0 Pid: 7600, comm: rsync Not tainted 2.6.24.2 #83  [<c014990e>] oom_kill_pr........
  • Seagate Drive 500GB Drive Dying


    This drive is clearly on the way out, the Kernel knows it but I'm surprised that SMART is not concerned.  I didn't blame Seagate for their past issues until now.  This hard drive has hardly been used and has not even been powered on for a year according to SMART. Home page is http://smartmontools.sourceforge.net/ === START OF INFORMATION SECTION === Model Family:     Seagate Barracuda 7200.11 Device........
  • Linux AHCI Hotswap Tips - Remember To Reread The Partition Table WITHOUT rebooting


    From the package "parted" you can use the command "partprobe" to re-read the partition table.  I really hate rebooting, and that's what I loved to hear about AHCI motherboards, that they allow hotswap so you don't have to reboot.  But that's only as good as the OS, if the OS does not reload the partition table you won't be able to do anything with that new drive you attached without rebooting.  Yes, even without re-reading the partiton table Linux will........
  • Picking an FTPD (vsftpd) Server in Linux Centos/Debian


    I decided on using yum to help me decide even though I normaly use proftpd I decided to see what else I could find. yum search ftp Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile  * rpmforge: ftp-stud.fht-esslingen.de  * base: mirrors.netdna.com  * updates: updates.interworx.info  * addons: yum.singlehop.com  * extras: mirrors.netdna.com rpmforge   ........
  • Compaq V2405CA Laptop - Unixbench Performance Test


    Here are the results, it is Sempron 3000+ AMD Mobile, 500Gig HDD, 512MB RAM with shared ATI Radeon graphics.      #    #  #    #  #  #    #          #####   ######  #    #   ####   #    #    #    #  ##   #  #   #  #&nb........
  • Fix/Solution for apt-get error: " E: Archive directory /var/cache/apt/archives/partial is missing."


    I thought I was being smart, I wanted to download some Debian packages so I went to /var/cache/apt/archives and did "rm -rf *" but then I couldn't use apt-get anymore.  I kept getting this error: E: Archive directory /var/cache/apt/archives/partial is missing. E: The list of sources could not be read. The solution was to recreate the "partial" directory inside /var/cache/apt/archives and then everything will be fine.........
  • PHP cannot access /usr/bin/openssl


    PHP cannot access /usr/bin/opensslI have verified the username that runs the process is able to access /usr/bin/openssl and it does exist but the PHP script is saying it doesn't exist: [code:1:1fd0f3abbe] if (!file_exists($OPENSSL)) { //echo "ERROR: OPENSSL $OPENSSL not foundn"; }[/code:1:1fd0f3abbe] I don't get itI can clearly see the contents of /usr/bin by using the PHP system fu........
  • Basic Port Listing


    Basic Port ListingHopefully someone finds this useful or at least interesting. http://www.sans.org/top20/#u9 Name Port Protocol Description Small services <20 tcp/udp small services FTP 21 tcp file transfer SSH 22 tcp login service TELNET 23 tcp login service SMTP 25 tcp mail TIME 37 tcp/udp time synchronization WINS 42 tcp/udp WINS replication DNS 53 udp naming service........
  • Have an OpenVZ VPS/Linux Virtual Private Server and nothing works right?


    A VPS Server I had just wasn't working right, code that I migrated there just wasn't working.  For example, it kept telling me the connection to the database was unsuccessful, halfway through iterating through results it already had. Then I realized it wasn't my code.  I checked my /proc/user_beancounters and found this: cat /proc/user_beancounters Version: 2.5 uid resource held maxheld barrier limit failcnt........
  • Fake PR Pagerank Identification - How do you know/check/verify the real PR(Pagerank)?


    Here is an example that I recently found, most PR checkers will say this domain is PR8 or will say "cannot analyze PR". The example is domain "bonserotica.com"  view Google's cache of the homepage and you'll see as in the picture below, it lists a different URL, which means they used a redirect to a high PR site to fool you and the PR checkers.........
  • OCFS2 crash


    When trying to even cd or ls the mounted OCFS2 partition it crashes.  I think this is a combination of VMWare Server's problem and the way I mounted and symlinked to it. More than anything this shows the problem and lack of forsight with VMWare, but also that OCFS2 is easily crashed if you do strange things. Output of /var/log/messages for OCFS2   Apr 10 15:57:45 localhost kernel: [84331.691258] Modules linked in: vmnet vmci vmmon ocfs2_stac........
  • Samba SMB Error - Server not using user level security and no password supplied. tree connect failed: NT_STATUS_WRONG_PASSWORD


    Server not using user level security and no password supplied. tree connect failed: NT_STATUS_WRONG_PASSWORD That happens when trying to use smbclient to connect to a share.  The weird thing is that I can authnenticate just fine from Windows XP. It is partially my mistake, I forgot this share does have a password.  I've tried authenticating with the correct user and also with "Guest" because this works in Windows.  In Linux I ........
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