Vzctl for upstream kernel

Warning: Running vzctl on upstream kernels is considered an experimental feature.

With this release vzctl tool is expected to run with Upstream Linux kernels. At the moment, it provides just basic functionality. It is currently possible to create and start a container with the same steps as one would use for a normal OpenVZ container. Other functionality may be present with limited functionality, while some are not present at all.

• The commands quotaon, convert, console, enter, exec and runscript are not expected to work. Checkpoint restore is also not possible, but upstream support for that is progressing very fast (See http://criu.org for details).

• Networking is available through the switches --netdev_add, --netif_add, and their respective deletion counterparts. IP mode networking (--ipadd / --ipdel) is currently not supported.

• Stopping a container once one is logged in is possible, in case the underlying kernel supports rebooting a PID namespace (> 3.4). Using vzctl, the "stop" command is not supported, unless accompanied by the --fast switch, which will simply forceably kill all processes in the container.

• Software that depend on information supplied by the proc filesystem may not work correctly, since there is not a full solution for full /proc virtualization. For instance, /proc/stat is not yet virtualized, and top will show distorted values.

• Setting resources like --physpages and --cpuunits work, but there their effect is dependent on what the current kernel supports, through the cgroups subsystem. When a particular cgroup file is present, it will be used. Currently, vzctl will search for the following files:
  • cpu.cfs_quota_us
  • cpu.shares
  • cpuset.cpus
  • memory.limit_in_bytes
  • memory.memsw.limit_in_bytes
  • memory.kmem.limit_in_bytes
  • memory.kmem.tcp.limit_in_bytes

Building and using

Upstream support is not enabled by default. To build it into vzctl, one needs to specify the --with-cgroup switch to configure:

 $ ./configure --with-cgroup

plus, of course, any other relevant options. Minimum versions for depencies is:

• iproute2 >= 3.0.0 (runtime only)
• libcg >= 0.38

For supported features, usage is expected to be the same as standard vzctl tool.