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{{Roughstub}}
 
{{Roughstub}}
  
This article describes the migration from Linux-VServer to OpenVZ.
+
Current document describes the migration from Linux-VServer based virtualization solution to OpenVZ.
  
== Details of migration process ==
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Description of challenge:
  
=== Initial conditions ===
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The challenge is migration from Linux-Vserver to OpenVZ by booting the OpenVZ kernel and updating the existing configs of
 +
utility level in purpose to make the existing guest OSes work over OpenVZ kernel.
  
The following example of Linux-VServer based solution was used for the experiment:
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Details of migration process. Step by step:
 +
 
 +
1. Initial conditions: the following example of Linux-VServer based solution was used for the experiment:
  
 
* Kernel linux-2.6.17.13 was patched by the patch-2.6.17.13-vs2.0.2.1.diff and rebuild;
 
* Kernel linux-2.6.17.13 was patched by the patch-2.6.17.13-vs2.0.2.1.diff and rebuild;
 
* Util-vserver-0.30.211 tools were used for creating containers;
 
* Util-vserver-0.30.211 tools were used for creating containers;
  
 +
<code>
 
   # vserver-info
 
   # vserver-info
 
   Versions:
 
   Versions:
Line 41: Line 45:
 
   vserver-Rootdir: /vservers
 
   vserver-Rootdir: /vservers
 
   #
 
   #
 +
</code>
  
 
VServer v345 was built using vserver vX build utility and populated by using the tarballed template of Fedora Core 4.
 
VServer v345 was built using vserver vX build utility and populated by using the tarballed template of Fedora Core 4.
 
   
 
   
 +
<code>
 
   # vserver v345 start
 
   # vserver v345 start
 
   Starting system logger:                                    [  OK  ]
 
   Starting system logger:                                    [  OK  ]
Line 70: Line 76:
 
   sh-2.05b#
 
   sh-2.05b#
 
   .........
 
   .........
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</code>
  
 
As a result we obtain running virtual environment v345:
 
As a result we obtain running virtual environment v345:
  
 +
<code>
 
   # vserver-stat
 
   # vserver-stat
 
   
 
   
Line 80: Line 88:
 
   
 
   
 
   #  
 
   #  
 +
</code>
  
=== Starting migration to OpenVZ ===
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2. Starting migration to OpenVZ: downloading and installing the stable OpenVZ kernel.
  
Downloading and installing the stable OpenVZ kernel.
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Install the OpenVZ kernel, as described in [[quick installation]].  
 
 
Install the OpenVZ kernel, as described in [[Quick installation]].  
 
  
 
After the kernel is installed, reboot the machine. After rebooting and logging in you will see the following reply on vserver-stat call:
 
After the kernel is installed, reboot the machine. After rebooting and logging in you will see the following reply on vserver-stat call:
  
 +
<code>
 
   # vserver-stat
 
   # vserver-stat
 
   can not change context: migrate kernel feature missing and 'compat' API disabled: Function not implemented
 
   can not change context: migrate kernel feature missing and 'compat' API disabled: Function not implemented
 +
  #
 +
</code>
  
 
It is a natural thing that now virtual environment v345 is unavailable. The following steps will be devoted to making it
 
It is a natural thing that now virtual environment v345 is unavailable. The following steps will be devoted to making it
 
work over OpenVZ kernel.
 
work over OpenVZ kernel.
  
=== Downloading and installing vzctl package ===
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3. Downloading and installing vzctl package
  
 
OpenVZ solution requires installing a set of tools: vzctl and vzquota packages. Download and install it, as described in [[quick installation]].
 
OpenVZ solution requires installing a set of tools: vzctl and vzquota packages. Download and install it, as described in [[quick installation]].
Line 102: Line 112:
 
Then launch the OpenVZ:
 
Then launch the OpenVZ:
  
 +
<code>
 
   # /sbin/service vz start
 
   # /sbin/service vz start
 
   Starting OpenVZ:                                          [  OK  ]
 
   Starting OpenVZ:                                          [  OK  ]
 
   Bringing up interface venet0:                              [  OK  ]
 
   Bringing up interface venet0:                              [  OK  ]
 
   Configuring interface venet0:                              [  OK  ]
 
   Configuring interface venet0:                              [  OK  ]
 +
  #
 +
</code>
  
 
Currently vzlist utility is unable to find any containers:
 
Currently vzlist utility is unable to find any containers:
 +
 +
<code>
 
   # vzlist
 
   # vzlist
 
   Containers not found
 
   Containers not found
 +
  #
 +
</code>
  
=== Updating different configurations ===
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4. Updating different configurations in purpose to make existing templates work
  
Get the existing guest OSs to the right place:
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Move the existing templates of guest OSs to the right place:
  
 +
<code>
 
   # cd /vz
 
   # cd /vz
 
   # mkdir private
 
   # mkdir private
   # mkdir private/345
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   # mkdir 345
 
   # mv /vservers/v345 /vz/private/345
 
   # mv /vservers/v345 /vz/private/345
In Debian Lenny the path is /var/lib/vz/private/345 instead.
+
</code>
In any case it is a good idea to have the guest file system in a dedicated partition or lvm container (shown in the example below) and just mount it there
 
instead of moving:
 
  # mkdir /var/lib/vz/private/345
 
  # mount /dev/mapper/vg01-lvol5 /var/lib/vz/private/345
 
  
 
Now it is time for creating configuration files for OpenVZ container. Use the basic sample
 
Now it is time for creating configuration files for OpenVZ container. Use the basic sample
 
configuration presented in /etc/sysconfig/vz-scripts/ve-vps.basic.conf-sample file:
 
configuration presented in /etc/sysconfig/vz-scripts/ve-vps.basic.conf-sample file:
  
 +
<code>
 
   # cd /etc/sysconfig/vz-scripts
 
   # cd /etc/sysconfig/vz-scripts
 
   # cp ve-vps.basic.conf-sample 345.conf
 
   # cp ve-vps.basic.conf-sample 345.conf
In Debian Lenny the configuration is located in /etc/vz/conf/ , in this case type:
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</code>
  # cd /etc/vz/conf
 
  # cp ve-vps.basic.conf-sample  345.conf
 
  
Now, let's set some parameters for the new container.
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Update the ON_BOOT string in 345.conf file by typing:
  
First, we need to tell which distro the container is running:
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<code>
   # echo "OSTEMPLATE=\"fedora-core-4\"" >> 345.conf
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  .....
   # echo "OSTEMPLATE=\"debian\"" >> 345.conf    (for Debian Lenny)
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  ONBOOT="yes"
 +
  .....
 +
</code>
 +
to make it boot on node restart, and add a couple of strings related to the
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particular container 345:
 +
<code>
 +
  .....
 +
   VE_ROOT="/vz/root/345"
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  VE_PRIVATE="/vz/private/345"
 +
  ORIGIN_SAMPLE="vps.basic"
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   HOSTNAME="test345.my.org"
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  IP_ADDRESS="192.168.0.145"
 +
  .....
 +
</code>
  
Then we set a few more parameters:
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And reboot the machine:
  vzctl set 345 --onboot yes --save # to make it start upon reboot
 
  vzctl set 345 --ipadd 192.168.0.145 --save
 
  vzctl set 345 --hostname test345.my.org --save
 
  
== Testing how the guest OSs successfully work over OpenVZ ==
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<code>
 +
  # reboot
 +
</code>
  
Now you can start a container:
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5. Testing how the guest OSs successfully work over OpenVZ. Reference to Users Guide of OpenVZ (vzctl).
  
# vzctl start 345
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After rebooting you will be able to see running container 345 that have been
 +
migrated from vserver:
  
and see if it's running:
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<code>
 
   # vzlist -a
 
   # vzlist -a
 
   CTID      NPROC  STATUS  IP_ADDR        HOSTNAME
 
   CTID      NPROC  STATUS  IP_ADDR        HOSTNAME
 
   345          5  running 192.168.0.145  test345.my.org
 
   345          5  running 192.168.0.145  test345.my.org
 +
  #
 +
</code>
  
You can run commands in it:
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And run commands on it:
  
 +
<code>
 
   # vzctl exec 345 ls -l
 
   # vzctl exec 345 ls -l
 
   total 48
 
   total 48
Line 176: Line 205:
 
   drwxr-xr-x  15 root    root        4096 Jul 27  2004 usr
 
   drwxr-xr-x  15 root    root        4096 Jul 27  2004 usr
 
   drwxr-xr-x  17 root    root        4096 Oct 26  2004 var
 
   drwxr-xr-x  17 root    root        4096 Oct 26  2004 var
 +
  #
 +
</code>
  
== Issues ==
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Potential issues:
 
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This work has in progress status. Some issues may take place with tuning the network for containers. To be continued.
=== Starting ===
 
 
 
If starting fails with a message '''Unable to start init, probably incorrect template''' either the /sbin/init file is missing in the guest file system, or just not executable. Or the guest file system is completely absent or dislocated. The proper path where you must place is specified in the vz.conf file, namely the parameter VE_PRIVATE. For Debian this file can be found in /etc/vz.
 
 
 
=== Networking ===
 
 
 
==== Starting networking in VEs ====
 
 
 
The vserver-originating containers do not initialize network at all. Thus one needs to use following command to enable networking start (inside of the migrated container):
 
 
 
update-rc.d networking defaults
 
 
 
==== Migrating your VServer Shorewall setup ====
 
 
 
If you had the [http://www.shorewall.net/ Shorewall firewall] running on the hardware node to route traffic to and from your guests, here are a couple of advices, provided you want a networking setup close to what you had with Vserver (i.e. running <code>vnet</code> interfaces, not <code>veth</code> ones) :
 
* do not use the <code>venet0</code> interface in Shorewall's configuration as the <code>vz</code> service starts after Shorewall (at least on Debian) and thus the interface does not exist when Shorewall starts. Do not use <code>detect</code> for the broadcast in <code>/etc/shorewall/interfaces</code>.
 
* for your VEs to be able to talk to each other, use the <code>routeback</code> option for <code>venet0</code> (and others) in <code>/etc/shorewall/interfaces</code>.
 
 
 
==== IP src from VEs ====
 
 
 
If you run a mail server in a VE, and if the hardware node has multiple network interfaces, you may have mail routing issues because of the originated IP address of the packets coming from the hardware node. Simply specify an interface in <code>/etc/vz/vz.conf</code> :
 
<pre>VE_ROUTE_SRC_DEV="iface_name"</pre>
 
 
 
=== Disk space information ===
 
 
 
Disk space information is empty. Do the following to fix:
 
rm /etc/mtab
 
ln -s /proc/mounts /etc/mtab
 
 
 
=== /dev ===
 
 
 
Vserver mounts /dev/pts filesystem for container transparently, whereas openvz does not. To compensate the ommission, you need to move aside /dev directory in the vserver-originating container and copy /dev directory from openvz based container.
 
 
 
=== Ubuntu udev ===
 
 
 
Additionally, Ubuntu based vservers have the udev package installed which prevents access to the console in openvz. This error message is an example of the problem:
 
 
 
# vzctl enter 345
 
enter into CT 345 failed
 
Unable to open pty: No such file or directory
 
 
 
The fix is to remove the udev package from the guest:
 
 
 
 
 
# vzctl exec 345 'dpkg --force-depends --purge udev'
 
(Reading database ... dpkg: udev: dependency problems, but removing anyway as you request:
 
  initramfs-tools depends on udev (>= 117-5).
 
15227 files and directories currently installed.)
 
Removing udev ...
 
Purging configuration files for udev ...
 
dpkg - warning: while removing udev, directory `/lib/udev/devices/net' not empty so not removed.
 
dpkg - warning: while removing udev, directory `/lib/udev/devices' not empty so not removed.
 
 
 
 
 
Now restart the container, you should now be able to use the console.
 
 
 
 
 
# vzctl restart 345
 
Restarting container
 
...
 
  <SNIP>
 
...
 
Container start in progress...
 
 
 
# vzctl enter 345
 
entered into CT 345
 
root@test:/#
 
 
 
=== /proc ===
 
 
 
The /proc filesystem is not automatically mounted by openvz. So the vserver needs to mount it itself. The simplests (not the best) way it can be done, is by sticking following command at the end of /etc/init.d/bootmisc.sh:
 
mount /proc
 
  
 
[[Category:HOWTO]]
 
[[Category:HOWTO]]

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