Reliability is the reason for me. We already have acceptable performance. I'm dealing with a client that provides IMAP services for multiple clients, and we're concerned about what happens in the event of a server failure on the machine with the HDDs. There's already RAID in place, but what if the mobo, PS, controller ... etc fails.
Allmost everybody has such requirements.
What I'd like to do is use Postgres with Slony to keep the IMAP folders on two completely seperate machines in real-time.
What about using Netapps (with snapmirrors or snapsync), then you'll get a rock stable storage system... and available on all machines in real-time :p
With maildir and nfs you'll can get a very stable system...
Using database (eg postgres) as storage system can be a good idea (mostly when you'd like to search something), but when it get corrupted or fragmented... then you'll have troubles....
This is my 0,02€ ... :)
/Savier
-- Xavier Beaudouin - Unix System Administrator & Projects Leader. President of Kazar Organization : http://www.kazar.net/ Please visit http://caudium.net/, home of Caudium & Camas projects