Sun Jun 24 10:14:45 EDT 2012

Snapshotting trick

Problem: I have a VM exporting NFS shares to its host.  This is a
nasty circular dependency that's hard to manage.  However, running
OpenWRT I recently found a trick used for filesystems to break a loop:
try to remount readonly when there is a dependency preventing unmount.
The same can be done for a vm: reboot in snapshot mode to allow for
proper save of the image, but keep serving the NFS.  After save, the
VM has no persistent state so can be killed at any time.