Cheap VPS & Xen Server

Residential Proxy Network - Hourly & Monthly Packages

Installing And Using OpenVZ On Debian Squeeze (AMD64)


In this HowTo I will describe how to prepare a Debian Squeeze server for OpenVZ. With OpenVZ you can create multiple Virtual Private Servers (VPS) on the same hardware, similar to Xen and the Linux Vserver project. OpenVZ is the open-source branch of Virtuozzo, a commercial virtualization solution used by many providers that offer virtual servers. The OpenVZ kernel patch is licensed under the GPL license, and the user-level tools are under the QPL license.

This howto is meant as a practical guide; it does not cover the theoretical backgrounds. They are treated in a lot of other documents in the web.

This document comes without warranty of any kind! I want to say that this is not the only way of setting up such a system. There are many ways of achieving this goal but this is the way I take. I do not issue any guarantee that this will work for you!

 

1 Preliminary Note

I’m using an x86_64 (amd64) system here. If you are on an i386 system, a few commands will be slightly different – I have added annotations to that parts.

 

2 Installing OpenVZ

An OpenVZ kernel and the vzctl, vzquota, and vzdump packages are available in the Debian Squeeze repositories, so we can install them as follows:

apt-get install linux-image-openvz-amd64 vzctl vzquota vzdump

(If you are on a i386 system, the kernel package is named linux-image-openvz-686.)

Create a symlink from /var/lib/vz to /vz to provide backward compatibility:

ln -s /var/lib/vz /vz

Open /etc/sysctl.conf and make sure that you have the following settings in it:

vi /etc/sysctl.conf

[...]
net.ipv4.conf.all.rp_filter=1
net.ipv4.icmp_echo_ignore_broadcasts=1
net.ipv4.conf.default.forwarding=1
net.ipv4.conf.default.proxy_arp = 0
net.ipv4.ip_forward=1
kernel.sysrq = 1
net.ipv4.conf.default.send_redirects = 1
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.eth0.proxy_arp=1
[...]

If you need to modify /etc/sysctl.conf, run

sysctl -p

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

[...]
# Controls which interfaces to send ARP requests and modify APR tables on.
NEIGHBOUR_DEVS=all
[...]

Finally, reboot the system:

reboot

If your system reboots without problems, then everything is fine!

Run

uname -r

and your new OpenVZ kernel should show up:

root@server1:~# uname -r
2.6.32-5-openvz-amd64
root@server1:~#

3 Using OpenVZ

Before we can create virtual machines with OpenVZ, we need to have a template for the distribution that we want to use in the virtual machines in the /var/lib/vz/template/cache directory. The virtual machines will be created from that template.

You can find a list of precreated templates on http://wiki.openvz.org/Download/template/precreated. For example, we can download a minimal Debian Squeeze template (x86_64) as follows:

cd /var/lib/vz/template/cache
wget http://download.openvz.org/template/precreated/contrib/debian-6.0-amd64-minimal.tar.gz

(If your host is an i386 system, you cannot use an amd64 template – you must use i386 templates then!)

I will now show you the basic commands for using OpenVZ.

To set up a VPS from the debian-6.0-amd64-minimal template (you can find it in /var/lib/vz/template/cache), run:

vzctl create 101 –ostemplate debian-6.0-amd64-minimal –config basic

The 101 must be a uniqe ID – each virtual machine must have its own unique ID. You can use the last part of the virtual machine’s IP address for it. For example, if the virtual machine’s IP address is 192.168.0.101, you use 101 as the ID.

If you want to have the vm started at boot, run

vzctl set 101 –onboot yes –save

To 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

Next we 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 145.253.2.75 –nameserver 8.8.8.8 –save

(Instead of using the vzctl set commands, 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

vzctl start 101

To set a root password for the vm, execute

vzctl exec 101 passwd

You can now either connect to the vm via SSH (e.g. with PuTTY), or you enter it as follows:

vzctl enter 101

To leave the vm’s console, type

exit

To stop a vm, run

vzctl stop 101

To restart a vm, run

vzctl restart 101

To delete a vm from the hard drive (it must be stopped before you can do this), run

vzctl destroy 101

To get a list of your vms and their statuses, run

vzlist -a

root@server1:~# vzlist -a
CTID      NPROC STATUS    IP_ADDR         HOSTNAME
101          8 running   192.168.0.101   test.example.com
root@server1:~#

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

vzctl exec 101 cat /proc/user_beancounters

server1:~# vzctl exec 101 cat /proc/user_beancounters
Version: 2.5
uid  resource           held    maxheld    barrier      limit    failcnt
101:  kmemsize         500737     517142   11055923   11377049          0
lockedpages           0          0        256        256          0
privvmpages        2315       2337      65536      69632          0
shmpages            640        640      21504      21504          0
dummy                 0          0          0          0          0
numproc               7          7        240        240          0
physpages          1258       1289          0 2147483647          0
vmguarpages           0          0      33792 2147483647          0
oomguarpages       1258       1289      26112 2147483647          0
numtcpsock            2          2        360        360          0
numflock              1          1        188        206          0
numpty                1          1         16         16          0
numsiginfo            0          1        256        256          0
tcpsndbuf         17856      17856    1720320    2703360          0
tcprcvbuf         32768      32768    1720320    2703360          0
othersockbuf       2232       2928    1126080    2097152          0
dgramrcvbuf           0          0     262144     262144          0
numothersock          1          3        120        120          0
dcachesize            0          0    3409920    3624960          0
numfile             189        189       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
server1:~#

The failcnt column is very important, it should contain only zeros; if it doesn’t, this means that the vm needs more resources than are currently allocated to the vm. Open the vm’s configuration file in /etc/vz/conf and raise the appropriate resource, then restart the vm.

To find out more about the vzctl command, run

man vzctl

  • OpenVZ: http://openvz.org/
  • Debian: http://www.debian.org/

Comments

comments