[horde] IMAP disk I/O slow

[Jaz]

I'm looking for advice in improving IMAP folder performance via IMP on a 
small Win2K box with one IDE disk.

(I'm also seeking advice in other forums on Linux vs Windows, Mercury/32 
vs other IMAP servers, IDE vs SCSI, etc.)

What happens is that opening a large inbox takes 30-seconds; Perfmon 
shows high disk I/O from my IMAP server process (Mercury/32), a disk 
queue of only 1.0, low CPU utilization, and low I/O by mysql, and 
apache, etc.

Mozilla (remotely) also takes 30 seconds to open the Inbox, but seems to 
cache, so that going back to Inbox from other folders is much faster -- 
just a few seconds. I understand that most IMAP clients cache folder 
contents, but it seems that IMP wants to grab the full folder list and 
close the session each time. An IMAP caching proxy might fix this (?) 
but I haven't succeeded in compiling one on win32. (and I run a bunch of 
other Win32 processes on this box -- that's why it's not Linux ;). I 
also have caching enabled (by file), but I don't see anything in the 
cache directory.

I was considering switching from IDE to SCSI to improve disk 
performance. Would switching from a Maxtor IDE (DiamondMAX) to a wide 
SCSI disk @ 10K on Utra160 drastically improve the time IMAP takes to 
fetch say, 2000 messages? (present IDE filesystem is NTFS + 4KB 
clusters), or will I need to get serious with say raid 0+1?

The system is a wimpy 1GHz P3 w/ 256MB, with a Maxtor D740X IDE (rated 
for 44MB/sec at OD & 24MB/sec at ID) which (via Dr. hardware) shows a 
respectable ~35MB/sec read and ~26MB/sec write, ~5.8ms access time. C: 
--> OS, cygwin, PHP, PEAR, and D: --> Apache, mysql, IMAP (apps and data).

And tho this system is only being used by just me, I'm looking to better 
understand disk/IMAP performance so when I scale a similar system 
(probably Linux) I'll know a bit more about mixing an all-in-one server.

I've looked through the Horde Performance Guide doc, will any of these 
measures make a noticable improvement in IMAP disk I/O, considering that 
this is such a lightly used system? Can anyone think either what other 
processes i should be monitoring, or how to improve IMAP folder and/or 
disk performance?

Thanks. Jaz