[horde] IMAP disk I/O slow

[cron@odi.com.br]

Jaz,

Running linux fedora core 3

Dont know why but on a amd 1.2 with 256 RAM is was taking about 60 seg for
imp to open a inbox with 30 to 40 mb, with 512 it was taking about 5 sec
with 1 1GB ram it is less them 1 sec.

Ângelo



----- Original Message ----- 
From: "Jaz" <horde at harbell.net>
To: <horde at lists.horde.org>
Sent: Wednesday, May 04, 2005 12:15 PM
Subject: [horde] IMAP disk I/O slow


>
> 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
>
>
> -- 
> Horde mailing list - Join the hunt: http://horde.org/bounties/#horde
> Frequently Asked Questions: http://horde.org/faq/
> To unsubscribe, mail: horde-unsubscribe at lists.horde.org
>