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XEN: Error about Xend not running when attempting to manage DomU's

This document (7002198) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10 Service Pack 1
SUSE Linux Enterprise Server 10 Service Pack 2

Situation

When attempting to manage, create, delete or start a Xen DomU (virtual machine) the process errors out. Xend is running.

ERR: Error: Unable to connect to xend: Connection refused. Is xend running?

Resolution

If the Xenstore managment database becomes corrupted, then the management of Xen virtual machines via "xm" commands, YaST, Virt-Manager or any management interface that uses the Xen API will not be able to manage the Xen hosts. Unmanaged DomU's will not be able to be started. A common cause of the corruption is when the volume where "/var" resides becomes full.

matching the error
The following steps will help you to match the error.
  1. Check the status of Xend
    service xend status
    should have a status of "running"
  2. Check the status of libvirtd
    service libvirtd status
    should have a status of "running"
  3. Check the /var/log/xend-debug.log
    tail /var/log/xen/xend-debug.log
    May have something similiar to
        self.__target(*self.__args, **self.__kwargs)
      File "/usr/lib64/python2.4/site-packages/xen/web/httpserver.py", line 312, in run
        (sock, addr) = self.accept()
      File "/usr/lib64/python2.4/site-packages/xen/web/httpserver.py", line 331, in accept
        return self.socket.accept()
      File "/usr/lib64/python2.4/socket.py", line 169, in accept
        sock, addr = self._sock.accept()
    error: (22, 'Invalid argument')

    Exception starting xend: not well-formed (invalid token): line 11, column 2
If the above matches, then this TID should be considered as a potential solution.

remove the xend database
Managed Xen DomU's store their definitions in /var/lib/xend/domains. The format uses a Python syntax. If the managed database becomes corrupted then you can lose the virtual machine definitions. If you have made any changes using "xm" commands, Virt-Manager or YaST to any virtual machine definition, then it is very likely that the configuration at install time has been altered. Because of this concern, it is strongly recommended that you backup the database before you do anything.

Therefore, it is recommended that you RENAME /var/lib/xend to /var/lib/xend.bk (or something similiar).
  1. Backup the /var/lib/xend. Renaming the directory will be sufficient.
  2. Shutdown the xend service
    service xend stop
  3. Shutdown the libvirtd service
    service libvirtd stop
  4. Make sure that /var/lib/xend does NOT exist. When xend is started again, this directory will be recreated.
  5. Start up the xend service
    service xend start
  6. Start up the libvirtd service
    service libvirtd start
  7. Test to make sure a simple "xm" command works. No DomU's will appear in the management database.
    xm list

unmanaged domains (legacy configuration)
If you do not use a managed database, use the DomU's in a clustered environment  then there is no further configuration needed. You should now be able to start, stop, create and otherwise manage your virtual machines normally.

managed domains
Managed domains are DomU's that are manipulated using the "xm" commands such as "block-attach", "network-attach", or are managed through YaST or Virt-Manager. If you use a graphical utility to manage the DomU then the DomU's are most likely managaged. These steps will help you recover the configuration for those DomU's.

  1. Go to the backup made of the /var/lib/xend.
  2. Go to the "domain" directory.
  3. There should directories for each DomU; the directories will be named with a GUID.
  4. For each of the GUID directories, there is a "config.sxp" that defines the virtual machines.
  5. Import the .sxp DomU configuration
    xm new -F config.sxp
  6. See if the re-imported DomU appears in a DomU listing
    xm list
  7. Test whether or not they start normally
    xm start DOMU
  8. Repeat step 5 through 7 for each directory in step 4

Additional Information

Running DomU's: If there are running DomU's, then you can safely follow the steps described in this TID.

Disclaimer

This Support Knowledgebase provides a valuable tool for NetIQ/Novell/SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7002198
  • Creation Date:16-DEC-08
  • Modified Date:27-APR-12
    • SUSESUSE Linux Enterprise Server
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