Performance and cheap storage

[Mark Hellman]

I have noticed that mail delivery (from Postfix to Cyrus using LMTP) can be
harsh in terms of I/O when several hundreds of messages are being delivered
at once. I have local mailing-lists with more than 1 thousand members and
when a 500 KB email is sent to the list, the server's load average
increases dramatically. This why I use SCSI disks for the Cyrus partition
directories, instead of SATA or ATA disks.

Now I would like to increase my users mailbox quota from 200 MB to 1 GB. 
The problem is that SCSI disks are expensive... So I though about the
following solution:
- Keeping mailboxes default partition mounted on a SCSI disk
- Putting each user's sub-mailbox on cheap IDE storage (with symlinks in
  the mailboxes partition directory) since access to sub-mailboxes is
  less frequent and less bursty. 
- Having a cron job that moves messages older than X days from the user's
  Inbox to a sub-mailbox (on IDE storage) to prevent SCSI disk getting full.

Is this symlinking feasible? Or is there another more efficient way to
achieve the same goal?


Mark