MS bogging under load ...

[Garry Glendown]

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Hi,

I've lately run into some load issues with MS ... I'm running the
current version, though looking at the mrtg stats, it seems the problem
may have been around ever since I upgraded to 4.31.6 and later ... I'm
running on a Celeron 2.2 w/512M of RAM ...

Anyway, usually, MS is handling the incoming mail load pretty decently
... the box has a daily load of around 20-25k mails or 500-800megs ...
spam ratio of anywhere between 50-75%, viruses/unwanted file types
around 10-20% (d at mn Windoze). I'm running ClamAV and F-Prot. Most of the
time, mail comes in and MS has to handle something like 2-5 mails per
batch, sometimes more. No sweat. At some point though, mails just start
backing up in the mqueue.in ... MS just goes to the configured maximum
of 30 mails per batch, and all 4 threads I've configured can't seem to
cope with the flow anymore (though checking the incoming mails in the
log/mail file doesn't appear any worse than from the regular flow). I've
read through the FAQ/MAQ and already moved the MS working directory to
the ram disk, which seemed to have helped at first, but I'm more or less
back to the beginning, with queues of up to 1000 and more mails building
up ...
At the times of the backlog, memory is pretty tight (which is why I
already limited MS to 4 threads, I think the default is 5 IIRC), but no
much swap used ... load avg runs around 4-5, with the CPU having some
idle time left ... (making me believe it might be something with the I/O
system - running on RAID1 ATA drives)

Question: where could I check into what might be causing this? I don't
think the above config should not be able to handle that kind of load ... !?

Tnx, -gg

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