Pause while selecting INBOX

[Gary Mills]

We have a moderately sized Cyrus installation with 2 TB of storage
and a few thousand simultaneous IMAP sessions.  When one of the
backup processes is running during the day, there's a noticable
slowdown in IMAP client performance.  When I start my `mutt' mail
reader, it pauses for several seconds at `Selecting INBOX'.  That
behavior disappears when the backup finishes.

Where's the first place to look for this problem?  I/O statistics
show a higher read bandwidth while the backup is running, but writes
still dominate.  The backup would typically read all of the files in
a single Cyrus partition.

-- 
-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-