FAQ

Contents

General

What is a container (Virtual Environment, Virtual Private Server, VPS, VE)?

See Container.

Who needs OpenVZ? How it can be used?

See Use cases.

What applications can run inside an OpenVZ container?

Most of applications can be installed to a container without any modifications. Oracle, DB/2, Weblogic, Websphere and other big applications run just find inside an OpenVZ container. Applications and services do not have to be aware of OpenVZ. However, direct access to hardware is not available by default.

How is OpenVZ different from other technologies?

See Introduction to virtualization.

How is OpenVZ updated and why it is secure?

See Security.

I want to show my appreciation to OpenVZ and put some logo to my site. Where to get it?

See Artwork.

Installation and upgrade

What hardware is supported by OpenVZ kernel?

See Virtuozzo HCL.

Why there are different kernel flavours available and what do they mean?

See Different kernel flavors (UP, SMP, ENTERPRISE, ENTNOSPLIT).

How do I rebuild the kernel?

See Kernel build.

What does 021stab018 in OpenVZ kernel version mean?

See Kernel versioning.

How can I check package signatures?

See Package signatures.

Is it possible to run x86 container on a x86_64 arch?

Sure :) We actually did some work on that to enable migration of x86 container from x86 to x86_64 and back, and to enable using 32-bit iptables in 32bit container on an x86_64 system.

What filesystems should I choose for saving my containers?

The safest choice is ext2/3 to save your containers. Remember that ReiserFS is less stable than ext2/3.

If you choose to use XFS, there will be no support for disk quota inside containers.

Networking

How do I set up VPN for a container?

See VPN via the TUN/TAP device.

What is veth and how do I use it?

See Virtual Ethernet device.

Why doesn't net-snmpd work on my containers?

See SNMPD in container.

User Beancounters

What are those User Beancounters?

See UBC.

What units are UBC parameters measured in?

See UBC parameter units.

How do I set up a container which is able to get X Mb of RAM?

See Setting UBC parameters.

I can not start a program in container: it reports out of memory. What do I do?

See Resource_shortage.

How can I reset failcnt in /proc/user_beancounters?

See UBC failcnt reset.

Troubleshooting

My kernel crashed. What should I do?

See When you have an oops.

I see a lot of processes in D state. What does that mean?

See Processes in D state.

Quick reference card for OpenVZ

openvz-reference-card.pdf