• How to install and setup LXC Containers (OpenVZ alternative) on Centos 6 / 7


    If you don't aleady have it, you'll need EPEL Install LXC yum -y install lxc lxc-templates Loaded plugins: fastestmirror Setting up Install Process Loading mirror speeds from cached hostfile * base: mirror.it.ubc.ca * epel: mirrors.kernel.org * extras: mirror.it.ubc.ca * updates:........
  • Linux named / bind how to dump, view and clear the cache!


    Do you hate it when your ISPhas old cached records because of a high TTLon the DNS record of the relevant domain? In plain English this means you often can't connect to a site or service because your ISP's DNS servers haven't gotten word of the new IP address (probably because they haven't checked). There are also some that are notorious for ignoring TTL and not updating records for days! But if you are lucky and smart enough to have your own Linux based DNS se........
  • iSCSI on Centos 7 Configuration and Setup Guide for Initiator and Target


    initiator = client target = server These are the first concepts you should understand which is that in iscsi essentially the "initiator" is the client and the "target" is the server. iSCSI is derived from the old fashioned SCSI that us oldtimers grew to love. The "i" stands for Internet and the SCSI stands for "Small Computers Systems Interface" (SCSI). iSCSI Target (Server)Setup targetcli is the pac........
  • 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


    Server Side Config 1.) First install nfs-utils yum -y install nfs-utils 2.) Configure nfs share Create a directory for your NFS share mkdir /datastore Create your NFS share in /etc/exports echo "/datastore 10.220.101.0/24(rw,sync,no_root_squash)" >> /etc/exports systemctl restart nfs........
  • 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 RAMis 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 Ican tell. The reason Iknow........
  • 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........
  • 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........
  • 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........
  • 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........
  • 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........
  • 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........
  • 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........
  • 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........
  • 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........
  • 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 IMHOon a production server). You may need to upgrade to PHP5.3 to run Joomla or many other reasons. Your host needs to use PHP 5.2.4 or higher to run this version of Jo........
  • 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........
  • 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 CPUand SSDwould 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........
  • 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........
  • 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........
  • 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........
  • 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........
  • 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 whenmy 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 [] oom_kill_pr........
  • 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........
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