"re-singleinstancestore" a partition?

[John Madden]

I need a sanity check here.

I had a single storage partition that I've grown to ~400GB to house
about 270,000 mailboxes.  I managed to reduce that number by around
115,000 by purging out accounts no one's logged into, still leaving
quite a mess of accounts.  I've been migrating them with some perl and
the mailbox move stuff in cyradm to four new partitions of 75GB each and
I'm finding that I'm very quickly running out of space due to the
breaking up of the singleinstancestore storage gains.  

To remedy this, I'm thinking about traversing the mailboxes on each
partition building a database of checksums to identify identical
messages, then replacing the duplicated content with hard links and
reconstructing the user's mailbox (for good measure, although it
shouldn't be necessary).  

I imagine the storage savings with this plan would be huge, but it
screams danger and I'm wondering if I should bother.  However, by my
calculations, I'll need another 600GB (for a total of 900GB) instead of
the current 400GB (which is actually only at 41% right now) and I simply
don't have the space.

The code to do this seems pretty trivial, but has anyone had to do this
before/is there a tool out there already that does it?

Thanks,
  John




-- 
John Madden
Sr. UNIX Systems Engineer
Ivy Tech Community College of Indiana
jmadden at ivytech.edu