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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:

directory holding all log file generated by the xend daemon and qemu-dm process.
  • 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.
  • Records error events from xend and its subsystems (from the framebuffer and Python scripts)
  • Logs events from hotplug events.
  • Event notifications from devices not coming online or network bridges not online are logged in this file.
  • 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.


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:

the standard directory for file-based guest images.
directory that hold the xend database which is generated every time the daemon is restarted.
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.
Holds dumps generate by virtual machines or when using the xm dump-core command.
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