ZFS now has deduplication support which is as easy as just setting a property on the file system.
zfs set dedup=on tank/src
Read Jeff Bonwick’s (the supremo source for ZFS) article as it covers everything you’d ever want to know about what deduplication is and the various strategies behind it. Can’t wait for it to be implemented in OpenSolaris 2010.02 its already been integrated into the ON source base.
Whilst on the subject of ZFS, there was a very good article posted on OSNews recently regarding the lack of
fsck for ZFS, it gives you a very good overview of ZFS, what COW really implies, how it differs from journaling filesystems found in Linux and ofcourse regarding