Splitting Server Into Equal Pieces

It is possible to create a Container configuration roughly representing a given fraction of the server. If you want to create such a configuration that up to 20 fully loaded Containers would be able to be simultaneously running on the given server, you can do it as follows:

# cd /etc/vz/conf

# vzsplit -n 20 -f mytest

Config /etc/vz/conf/ve-mytest.conf-sample was created

Notice that the configuration produced depends on the given server resources. Therefore, it is important to validate the resulted configuration file before trying to use it, which is done with the help of the vzcfgvalidate utility. For example:

# vzcfgvalidate ve-mytest.conf-sample

Recommendation: kmemsize.lim-kmemsize.bar should be > 253952 \

(currently, 126391)

Recommendation: dgramrcvbuf.bar should be > 132096 (currently, 93622)

The number of Containers you can run on the server is actually several times greater than the value specified in the command line because Containers normally do not consume all the resources that are guaranteed to them. To illustrate this idea, let us look at the Container created from the configuration produced above:

# pctl create 101 --ostemplate redhat-el5-x86 --config mytest

Creating Container private area (redhat-el5-x86)

Container is mounted

Postcreate action done

Container is unmounted

Container private area created

Container registered successfully

# pctl set 101 --ipadd 192.168.1.101 --save

Saved parameters for Container 101

# pctl start 101

Starting Container ...

Container is mounted

...

# vzcalc 101

Resource Current(%) Promised(%) Max(%)

Memory 0.53 1.90 6.44

As is seen, if Containers use all the resources guaranteed to them, then around 20 Containers can be simultaneously running. However, taking into account the Promised column output, it is safe to run 40-50 such Containers on this server.

Note : If you generate a Container configuration sample using the vzsplit command line utility, the resulting Container sample is put to the /etc/vz/conf directory. This sample can then be used by pctl create when creating a new Container on its basis.