Physical to container

A rough description of how to migrate existing physical server into a VE.

What you need to do in order to migrate is:

• Prepare an “empty” VE. For OpenVZ this would mean the following (assume you choose VE ID of 123):

mkdir /vz/root/123 /vz/private/123
cat /etc/vz/conf/ve-vps.basic.conf-sample > /etc/vz/conf/123.conf

• Stop most services on a machine to be migrated. “Most” means services such as web server, databases and the like — so you will not loose your data. Just leave the bare minimum (including ssh).

• Copy all your data from the machine to an OpenVZ box. Say you'll be using VE with ID of 123, then all the data should be placed to /vz/private/123/ directory (so there will be directories such as /vz/private/123/bin, etc, var and so on). This could be done by scp or rsync.

• Set some VE parameters. You have to add OSTEMPLATE=xxx line to /etc/vz/conf/123.conf file, where xxx would be distribution name (like debian-3.0) for vzctl to be able to make changes specific for this distribution.

Also, you have to supply an IP for a new VE:

vzctl set 123 --ipadd x.x.x.x --save

• You have to edit some files inside a VE. For example, virtual server does not have real ttys, so you have to disable getty in /etc/inittab (i. e. /vz/private/123/etc/inittab). Also, link /etc/mtab to /proc/mounts.

sed -i -e '/getty/d' /vz/private/123/etc/inittab
rm -f /vz/private/123/etc/mtab
ln -s /proc/mounts /vz/private/123/etc/mtab 

Also check that:

- fstab is empty ; fstab has to be empty.
- /dev/ptymx exists
  if it does not exist, create with: vzctl exec 123 mknod /dev/ptmx c 5 2
- check if /dev/pts exists
   it's a dir, if it does not exist, create with vzctl exec 123 mkdir /dev/pts

There might be other adjustments needed. Please add if you have more info.

• Try to start your new VE:

vzctl start 123

• If your node starts but you can not enter it, you should be able to execute commands in it.

check if devpts is mounted.
vzctl exec 123 mount

If it is not mounted, mount it vzctl exec 123 mount -t devpts none /dev/pts If it does not exist, please check above to create it correctly.

If anything goes wrong, try to find out why and fix. If you have enough Linux experience, it can be handled.

Also check out IRC and please report back on this page.

Success Stories

- Debian 3.1 Sarge with MySQL, apache2, PowerDNS --stoffell 08:41, 8 February 2007 (EST)