Newer xfs file systems are created with lazy-count enabled, which will not be mounted by Crossmeta XFS.
In order to work with Crossmeta one has to disable this lazy-count by issuing
xfs_admin -c 0
-or- create one with lazy-count=0
mkfs.xfs -l lazy-count=0
This lazy-count feature is like steroid to XFS metadata operations!!
http://oss.sgi.com/archives/xfs/2010-03/msg00170.html