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Chapter 37. Troubleshooting the Xen para-virtualized drivers

This chapter deals with issues you may encounter with Xen hosts and fully virtualized Red Hat Enterprise Linux guests using the para-virtualized drivers.

37.1. Red Hat Enterprise Linux 5 Virtualization log file and directories

Red Hat Enterprise Linux 5 Virtualization related log file

In Red Hat Enterprise Linux 5, the log file written by the xend daemon and the qemu-dm process are all kept in the following directories:

/var/log/xen/
directory holding all log file generated by the xend daemon and qemu-dm process.
xend.log
  • This logfile is used by xend to log any events generate by either normal system events or operator initiated events.
  • virtual machine operations such as create, shutdown, destroy etc are all logged in this logfile.
  • Usually this logfile will be the first place to look at in the event of a problem. In many cases you will be able to identify the root cause by scanning the logfile and review the entries logged just prior to the actual error message.
xend-debug.log
  • Records error events from xend and its subsystems (from the framebuffer and Python scripts)
xen-hotplug.log
  • Logs events from hotplug events.
  • Event notifications from devices not coming online or network bridges not online are logged in this file.
qemu-dm.PID.log
  • This file is created by the qemu-dm process which is started for each fully virtualized guest.
  • The PID is replaced with the PID of the process of the related qemu-dm process
  • You can retrieve the PID for a given qemu-dm process using the ps command and in looking at the process arguments you can identify the virtual machine the qemu-dm process belongs to.
If you are troubleshooting a problem with the virt-manager application you can also review the logfile generated by it. The logfile for virt-manager will be in a directory called .virt-manager in the user's home directory whom ran virt-manager. This directory will usually be ~/.virt-manager/virt-manager.

Note

The logfile is overwritten every time you start virt-manager. If you are troubleshooting a problem with virt-manager make sure you save the logfile before you restart virt-manager after an error has occurred.
Red Hat Enterprise Linux 5 Virtualization related directories

There are a few other directories and files which may be of interest when troubleshooting a Red Hat Enterprise Linux 5 Virtualization environment:

/var/lib/libvirt/images/
the standard directory for file-based guest images.
/var/lib/xen/xend-db/
directory that hold the xend database which is generated every time the daemon is restarted.
/etc/xen/
Stores a number of configuration files for the Xen hypervisor.
  • /etc/xen/xend-config.sxp is the main configuration for the xend daemon. The xend-config.sxp file enables or disables migration and other features not configured by libvirt. Use the libvirt tools for all other features.
/var/lib/xen/dump/
Holds dumps generate by virtual machines or when using the xm dump-core command.
/proc/xen/
Stores xen-kernel information in the following files:
  • /proc/xen/capabilities
  • /proc/xen/privcmd
  • /proc/xen/balloon
  • /proc/xen/xenbus
  • /proc/xen/xsd_port
  • /proc/xen/xsd_kva