Using And Installing OpenVZ On CentOS 6.3

multiple Virtual Private Servers (VPS) by the use of OpenVZ on the same hardware, similar to Xen and the Linux Vserver projectThe OpenVZ kernel patch is licensed under the GPL license, and the user-level tools are under the QPL license

 

1 Installing OpenVZ

To Install of OpenVZ wwant to add 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

 

open openvz.repo

 

vi openvz.repo

 

[...]
[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
[...]

 

few different OpenVZ kernels The command used for that is

 

yum search vzkernel

 

The available kernels are

 

[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 files used by the Linux kernel
vzkernel-headers.i686 : Header files for the Linux kernel for use by glibc
vzkernel-headers.x86_64 : Header files for the Linux kernel for use by glibc
[…]
[root@server1 yum.repos.d]#

 

Pick one and install

yum install vzkernel

 

automatically update the GRUB bootloader open /boot/grub/menu.lst; the first kernel stanza should now contain the new OpenVZ kernel the value of default is 0 the OpenVZ kernel is booted automatically instead of 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

install some OpenVZ user tools

 

yum install vzctl vzquota

Open /etc/sysctl.conf the following settings in it

 

vi /etc/sysctl.conf

 

<pre>[...]
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
[...]</pre>
to modify /etc/sysctl.conf, run

&nbsp;

sysctl –p

&nbsp;

afterwards.

The following step is important if the IP addresses of your virtual machines are from a different subnet than the host system’s IP address. If you don’t do this, networking will not work in the virtual machines!

Open /etc/vz/vz.conf and set NEIGHBOUR_DEVS to all:

vi /etc/vz/vz.conf
[...]
NEIGHBOUR_DEVS=all
[...]

SELinux should be disabled if you want to use OpenVZ. 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

 

Atlast reboot the system

 

Reboot

 

System reboots without problems nothing is wrong

Run

uname –r

and your new OpenVZ kernel should show up:

[root@server1 ~]# uname -r
2.6.32-042stab057.1
[root@server1 ~]#

2 Using OpenVZ

Before creating virtual machines with OpenVZ must to have a template for the distribution that we want to use in the virtual machines in the /vz/template/cache directory. from that template virtual machines will be created.

 

To use CentOS 6 in my virtual machines want to download a CentOS 6 template

 

cd /vz/template/cache

wget http://download.openvz.org/template/precreated/centos-6-x86_64.tar.gz

 

The basic commands for using OpenVZ

set up a VPS from the CentOS 6 template, run:

 

vzctl create 101 –ostemplate centos-6-x86_64 –config basic

 

uniqe ID must be 101 each virtual machine must have own unique ID. if the virtual machine’s IP address is 192.168.0.101, you use 101 as the ID

 

To have the vm started at boot, run

 

vzctl set 101 –onboot yes –save

 

Set a hostname and IP address for the vm, run

 

vzctl set 101 --hostname test.example.com --save
vzctl set 101 --ipadd 192.168.0.101 –save

 

Set the number of sockets to 120 and assign a few nameservers to the vm

vzctl set 101 --numothersock 120 --save
vzctl set 101 --nameserver 8.8.8.8 --nameserver 8.8.4.4 --nameserver 145.253.2.75 –save

 

You can as well directly edit the vm’s configuration file which is stored in the /etc/vz/conf directory. If the ID of the vm is 101, then the configuration file is /etc/vz/conf/101.conf

 

 

To start the vm, run

&nbsp;

vzctl start 101

&nbsp;

Set a root password for the vm

&nbsp;

vzctl exec 101 passwd

&nbsp;

Connect to the vm via SSH

&nbsp;

vzctl enter 101

&nbsp;

Leave the vm's console

Exit

&nbsp;

Stop a vm, run

vzctl stop 101

&nbsp;

Restart a vm, run

vzctl restart 101

&nbsp;

Delete a vm from the hard drive

vzctl destroy 101

&nbsp;

Get a list of your vms and their statuses, run

vzlist –a

root@server1 cache]# vzlist -a
CTID      NPROC STATUS    IP_ADDR         HOSTNAME
101         14 running   192.168.0.101   test.example.com
[root@server1 cache]#

To find out about the resources allocated to a vm, run

vzctl exec 101 cat /proc/user_beancounters

[root@server1 cache]# vzctl exec 101 cat /proc/user_beancounters
Version: 2.5
uid  resource           held    maxheld    barrier      limit    failcnt
101:  kmemsize        1508202    1661695   11055923   11377049          0
lockedpages           0          0        256        256          0
privvmpages        5430       7102      65536      69632          0
shmpages            381        381      21504      21504          0
dummy                 0          0          0          0          0
numproc              19         21        240        240          0
physpages          2489       2775          0 2147483647          0
vmguarpages           0          0      33792 2147483647          0
oomguarpages       2489       2775      26112 2147483647          0
numtcpsock            5          5        360        360          0
numflock              3          4        188        206          0
numpty                0          1         16         16          0
numsiginfo            0          2        256        256          0
tcpsndbuf         44720          0    1720320    2703360          0
tcprcvbuf         81920          0    1720320    2703360          0
othersockbuf      13144      14356    1126080    2097152          0
dgramrcvbuf           0       8380     262144     262144          0
numothersock         11         13        120        120          0
dcachesize            0          0    3409920    3624960          0
numfile             503        531       9312       9312          0
dummy                 0          0          0          0          0
dummy                 0          0          0          0          0
dummy                 0          0          0          0          0
numiptent            10         10        128        128          0
[root@server1 cache]#

The failcnt column is very important find out more about the vzctl command, run

Man vzctl

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