Description of problem:

Currently, even with device-mapper, there's a good chance that a device will
have a different major/minor number on two different hosts.  This causes
problems with NFS exports because they use the device number to validate file
handles on reboots.

Rgmanager simultates reboots on failover, but unfortauntely, since the device
might change between nodes, all of the filehandles will become invalid (stale).

Fortunately, nfsd provides an export option, "fsid=x", were X is a symbolic file
system ID which should be used instead of the device major/minor numbers in the
file handle.  On a failover, if the fsid matches, the client file handles are
considered good irrespective of whether or not the actual device numbers match.

Making this an inherit-able piece allows users to specify file system IDs as a
property of the mount - rather than the individual client exports.  This is what
most people would want.  Without this, nfsclient resources can not be reused;
the user must create new ones for each service...