How to Install and Use OpenVZ on CentOS 6.3

Instructions

• 1

  How to install OpenVZ
  
  Before installing OpenVZ, you have to include the OpenVZ repository to yum:
  
  cd /etc/yum.repos.d
  wget http://download.openvz.org/openvz.repo
  rpm --import http://download.openvz.org/RPM-GPG-Key-OpenVZ
  
  Now, open openvz.repo...
  
  vi openvz.repo
  
  ... and disable the [openvz-kernel-rhel5] repository (enabled=0) and enable the [openvz-kernel-rhel6] repository instead (enabled=1):
  
  [...]
  
  [openvz-kernel-rhel6]
  
  name=OpenVZ RHEL6-based kernel
  
  #baseurl=http://download.openvz.org/kernel/branches/rhel6-2.6.32/current/
  
  mirrorlist=http://download.openvz.org/kernel/mirrors-rhel6-2.6.32
  
  enabled=1
  
  gpgcheck=1
  
  gpgkey=http://download.openvz.org/RPM-GPG-Key-OpenVZ
  
  
  
  [openvz-kernel-rhel5]
  
  name=OpenVZ RHEL5-based kernel
  
  #baseurl=http://download.openvz.org/kernel/branches/rhel5-2.6.18/current/
  
  mirrorlist=http://download.openvz.org/kernel/mirrors-rhel5-2.6.18
  
  enabled=0
  
  gpgcheck=1
  
  gpgkey=http://download.openvz.org/RPM-GPG-Key-OpenVZ
• 2

  There are some different types of OpenVZ kernels in the repository. This command – yum search vzkernel - will feature the available kernels.
  
  [root@server1 yum.repos.d]# yum search vzkernel
  [...]
  vzkernel.i686 : The Linux kernel
  vzkernel.x86_64 : The Linux kernel
  vzkernel-devel.i686 : Development package for building kernel modules to match the kernel
  vzkernel-devel.x86_64 : Development package for building kernel modules to match the kernel
  vzkernel-firmware.noarch : Firmware wp-content/uploads used by the Linux kernel
  vzkernel-headers.i686 : Header wp-content/uploads for the Linux kernel for use by glibc
  vzkernel-headers.x86_64 : Header wp-content/uploads for the Linux kernel for use by glibc
  [...]
  [root@server1 yum.repos.d]#
  
  Select one of them and installed it according to a given procedure.
  
  yum install vzkernel
• 3

  By doing this, GRUB bootloader will also be automatically updated. But anyhow, launch /boot/grub/menu1st; and the first kernel stanza is now equipped with the new OpenVZ kernel. One thing to keep in mind is that default value should be 0 in order to automatically boot the first kernel (the OpenVZ kernel) as an alternative to the default CentOS kernel.
  
  vi /boot/grub/menu.lst
  
  # grub.conf generated by anaconda
  
  #
  
  # Note that you do not have to rerun grub after making changes to this file
  
  # NOTICE:  You have a /boot partition.  This means that
  
  #          all kernel and initrd paths are relative to /boot/, eg.
  
  #          root (hd0,0)
  
  #          kernel /vmlinuz-version ro root=/dev/mapper/vg_server1-lv_root
  
  #          initrd /initrd-[generic-]version.img
  
  #boot=/dev/sda
  
  default=0
  
  timeout=5
  
  splashimage=(hd0,0)/grub/splash.xpm.gz
  
  hiddenmenu
  
  title OpenVZ (2.6.32-042stab057.1)
  
  root (hd0,0)
  
  kernel /vmlinuz-2.6.32-042stab057.1 ro root=/dev/mapper/vg_server1-lv_root rd_LVM_LV=vg_server1/lv_root rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto  KEYBOARDTYPE=pc KEYTABLE=de rd_LVM_LV=vg_server1/lv_swap rd_NO_DM rhgb quiet
  
  initrd /initramfs-2.6.32-042stab057.1.img
  
  title CentOS (2.6.32-279.el6.x86_64)
  
  root (hd0,0)
  
  kernel /vmlinuz-2.6.32-279.el6.x86_64 ro root=/dev/mapper/vg_server1-lv_root rd_LVM_LV=vg_server1/lv_root rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto  KEYBOARDTYPE=pc KEYTABLE=de rd_LVM_LV=vg_server1/lv_swap rd_NO_DM rhgb quiet
  
  initrd /initramfs-2.6.32-279.el6.x86_64.img
  
  
• 4

  In order to install some OpenVZ user tools, follow this code:
  
  yum install vzctl vzquota
  
  Now, open /etc/sysctl.conf and make sure that you have the following settings in it:
  
  vi /etc/sysctl.conf
  
  [...]
  
  net.ipv4.ip_forward = 1
  
  net.ipv4.conf.default.proxy_arp = 0
  
  net.ipv4.conf.all.rp_filter = 1
  
  kernel.sysrq = 1
  
  net.ipv4.conf.default.send_redirects = 1
  
  net.ipv4.conf.all.send_redirects = 0
  
  net.ipv4.icmp_echo_ignore_broadcasts=1
  
  net.ipv4.conf.default.forwarding=1
  
  [...]
• 5

  In case you want some modifications in /etc/sysctl.cof, run
  sysctl -p
  
  This is an important step for all those who have IP addresses of their virtual machines from a separate subnet than the IP address of a host system. In case you forget to do this, networking will not be done in the virtual machines.
  
  Open /etc/vz/vz.conf and set NEIGHBOUR_DEVS to all:
  
  vi /etc/vz/vz.conf
  
  [...]
  
  NEIGHBOUR_DEVS=all
  
  [...]
• 6

  In order to use OpenVZ, you have to disable SELinux. Open /etc/sysconfig/selinux and set the value of SELINUX to disabled:
  
  vi /etc/sysconfig/selinux
  
  # This file controls the state of SELinux on the system.
  
  # SELINUX= can take one of these three values:
  
  #     enforcing - SELinux security policy is enforced.
  
  #     permissive - SELinux prints warnings instead of enforcing.
  
  #     disabled - No SELinux policy is loaded.
  
  SELINUX=disabled
  
  # SELINUXTYPE= can take one of these two values:
  
  #     targeted - Targeted processes are protected,
  
  #     mls - Multi Level Security protection.
  
  SELINUXTYPE=targeted
• 7

  Now reboot the system:
  
  reboot
  
  
  If your system reboots without any issue, then go ahead.
  
  Run
  
  uname –r
  
  and your new OpenVZ kernel should show up:
  [root@server1 ~]# uname -r
  2.6.32-042stab057.1
  [root@server1 ~]#