Reporting OpenVZ problem

To support OpenVZ users we maintain Support forum and Users mailing list. If you analyze an activity at the forum, then you'll find out, that the very big part of all messages there are requests to users to provide an additional information about their environments. Because of it the time between the report of a problem and its solution is sometimes much more longer, than it could be.

The aim of this article is to clue up users, what information they should report when they encounter OpenVZ related problem. We hope that it will make our support service more effective.

Contents

You should always report

• clear problem description

It is necessary not just to describe the problem, but also post real commands, and real output on console. It is useful to run commands with --verbose option.

• Kernel information
  • kernel version, architecture and flavour (uname -a)
  • origin of your binary kernel (RPM from openvz.org, other repository, compiled from sources, ...)
  • .config file (if you compiled the kernel)
• Linux distribution used on HN
• vzctl information
  • vzctl --version
• OpenVZ environment information
  • /etc/vz/vz.conf file
  • /etc/vz/<veid>.conf file, where <veid> is an id of VE in question.
• Various log files
  • /var/log/messages
  • /var/log/vzctl.log
  • Other

If other programs are involved in your problem, try to run they with increased verbosity and attach appropriate log files, if exist.

A program fails to run

The most viable tool here is strace. Seestracing a program.

Network related problem

• interface/routing/filter configuration

You should run these commands in VE and on HN

# ip a l
# ip r l
# iptables -L
# iptables -t nat -L
# cat /proc/sys/net/ipv4/ip_forwarding

Of course, if you have public IPs you should carefully mask them. For example: 194.85.83.97 -> X.Y.83.97.

Kernel Oops

"When you have an oops" article explains how to identify Oops and what you should do when it happens. The key moment is that you should send us the full Ooops text. Sometimes it can be easily obtained from /var/log/messages file or dmesg, but sometimes, you see Oops on the screen and the system is completely stuck. In such situation you should produce Remote console setup. Actually each production server should have setuped remote console.

Access to the node

In some cases, a remote access to the problem node is the fastest way to diagnose and fix a problem, so sometimes an OpenVZ developer can request such access from you. Note that in should be a root access (either directly, or via sudo) to the hardware node.

In case you can provide an access, post login information via forum PM or by e-mail, or ask for a public SSH key.

Warning: Do not post any login details to public forums, mailing lists etc.