Migration from Linux-VServer to OpenVZ
This article is a stub/rough-draft. You can help OpenVZ Wiki by expanding it. This article describes the migration from Linux-VServer to OpenVZ.
Contents
Details of migration process
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;
- Util-vserver-0.30.211 tools were used for creating containers;
# vserver-info
Versions:
Kernel: 2.6.17.13-vs2.0.2.1
VS-API: 0x00020002
util-vserver: 0.30.211; Dec 5 2006, 17:10:21
Features:
CC: gcc, gcc (GCC) 3.4.3 20041212 (Red Hat 3.4.3-9.EL4)
CXX: g++, g++ (GCC) 3.4.3 20041212 (Red Hat 3.4.3-9.EL4)
CPPFLAGS:
CFLAGS: '-g -O2 -std=c99 -Wall -pedantic -W -funit-at-a-time'
CXXFLAGS: '-g -O2 -ansi -Wall -pedantic -W -fmessage-length=0 -funit-at-a-time'
build/host: i686-pc-linux-gnu/i686-pc-linux-gnu
Use dietlibc: yes
Build C++ programs: yes
Build C99 programs: yes
Available APIs: v13,net
ext2fs Source: kernel
syscall(2) invocation: alternative
vserver(2) syscall#: 273/glibc
Paths:
prefix: /usr/local
sysconf-Directory: ${prefix}/etc
cfg-Directory: ${prefix}/etc/vservers
initrd-Directory: $(sysconfdir)/init.d
pkgstate-Directory: ${prefix}/var/run/vservers
vserver-Rootdir: /vservers
#
VServer v345 was built using vserver vX build utility and populated by using the tarballed template of Fedora Core 4.
# vserver v345 start Starting system logger: [ OK ] Initializing random number generator: [ OK ] Starting crond: l: [ OK ] Starting atd: [ OK ] # vserver v345 enter [/]# ls -l total 44 drwxr-xr-x 2 root root 4096 Oct 26 2004 bin drwxr-xr-x 3 root root 4096 Dec 8 17:16 dev drwxr-xr-x 27 root root 4096 Dec 8 15:21 etc -rw-r--r-- 1 root root 0 Dec 8 15:33 halt drwxr-xr-x 2 root root 4096 Jan 24 2003 home drwxr-xr-x 7 root root 4096 Oct 26 2004 lib drwxr-xr-x 2 root root 4096 Jan 24 2003 mnt drwxr-xr-x 3 root root 4096 Oct 26 2004 opt -rw-r--r-- 1 root root 0 Dec 7 20:17 poweroff dr-xr-xr-x 80 root root 0 Dec 8 11:38 proc drwxr-x--- 2 root root 4096 Dec 7 20:17 root drwxr-xr-x 2 root root 4096 Oct 26 2004 sbin drwxrwxrwt 2 root root 40 Dec 8 17:16 tmp drwxr-xr-x 15 root root 4096 Jul 27 2004 usr drwxr-xr-x 17 root root 4096 Oct 26 2004 var [/]# sh sh-2.05b# .........
As a result we obtain running virtual environment v345:
# vserver-stat CTX PROC VSZ RSS userTIME sysTIME UPTIME NAME 0 51 90.9M 26.3M 0m58s75 2m42s57 33m45s93 root server 49153 4 10.2M 2.8M 0m00s00 0m00s11 21m45s42 v345 #
Starting migration to OpenVZ
Downloading and installing the stable OpenVZ kernel.
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:
# vserver-stat can not change context: migrate kernel feature missing and 'compat' API disabled: Function not implemented
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.
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.
If rpm complains about unresolved dependencies, you'll have to satisfy them first, then repeat the installation. Then launch the OpenVZ:
# /sbin/service vz start Starting OpenVZ: [ OK ] Bringing up interface venet0: [ OK ] Configuring interface venet0: [ OK ]
Currently vzlist utility is unable to find any containers:
# vzlist Containers not found
Updating different configurations
Move the existing guest OSs to the right place:
# cd /vz # mkdir private # mkdir private/345 # mv /vservers/v345 /vz/private/345
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:
# cd /etc/sysconfig/vz-scripts # cp ve-vps.basic.conf-sample 345.conf
Now, let's set some parameters for the new container.
First, we need to tell which distro the container is running:
# echo "OSTEMPLATE="fedora-core-4" >> 345.conf
Then we set a few more parameters:
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
Now you can start a container:
# vzctl start 345
and see if it's running:
# vzlist -a CTID NPROC STATUS IP_ADDR HOSTNAME 345 5 running 192.168.0.145 test345.my.org
You can run commands in it:
# vzctl exec 345 ls -l total 48 drwxr-xr-x 2 root root 4096 Oct 26 2004 bin drwxr-xr-x 3 root root 4096 Dec 11 12:42 dev drwxr-xr-x 27 root root 4096 Dec 11 12:44 etc -rw-r--r-- 1 root root 0 Dec 11 12:13 fastboot -rw-r--r-- 1 root root 0 Dec 8 15:33 halt drwxr-xr-x 2 root root 4096 Jan 24 2003 home drwxr-xr-x 7 root root 4096 Oct 26 2004 lib drwxr-xr-x 2 root root 4096 Jan 24 2003 mnt drwxr-xr-x 3 root root 4096 Oct 26 2004 opt -rw-r--r-- 1 root root 0 Dec 7 20:17 poweroff dr-xr-xr-x 70 root root 0 Dec 11 12:42 proc drwxr-x--- 2 root root 4096 Dec 7 20:17 root drwxr-xr-x 2 root root 4096 Dec 11 12:13 sbin drwxrwxrwt 2 root root 4096 Dec 8 12:40 tmp drwxr-xr-x 15 root root 4096 Jul 27 2004 usr drwxr-xr-x 17 root root 4096 Oct 26 2004 var
Issues
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):
cd /etc/rcS.d ln -s ../init.d/networking S40networking
Migrating your VServer Shorewall setup
If you had the 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 vnet interfaces, not veth ones) :
- do not use the
venet0interface in Shorewall's configuration as thevzservice starts after Shorewall (at least on Debian) and thus the interface does not exist when Shorewall starts. Do not usedetectfor the broadcast in/etc/shorewall/interfaces. - for your VEs to be able to talk to each other, use the
routebackoption forvenet0(and others) in/etc/shorewall/interfaces.
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 /etc/vz/vz.conf :
VE_ROUTE_SRC_DEV="iface_name"
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.
/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