The only other reference I could find was this:
As with the author of the linked post I saw countless errors such as:
No handlers could be found for logger "xend"
Error: Disk isn't accessible (or equivalent)
Needless to say, I was also annoyed but I managed to find a fix that didn't require disabling selinux:
mount your other volume here:
/var/lib/xen/images
(the default location for Xen images)
restorecon /var/lib/xen/images
then run restorecon on all vm files within /var/lib/xen/images
( cd /var/lib/xen/images; restorecon *; )
selinux knows that /var/lib/xen/images should be the location of Xen VM images, so it will adjust their selinux flags accordingly when running restorecon, and then things will work.
Don't forget to update your /etc/xen/auto VM definitions to point to the new vm file locations.
Upon rebooting, your /etc/xen/auto/ VMs should now start appropriatly.