> The hardware is a Compaq Prolian 7000 whith 1.5 gb RAM and RAID 5 storage
> (100
> gb). There are 2 partition (both ext3) / and /var. qmail and vpopmail are
> installed in /var.
>
> The mail server has about 200 hosted domain but only one is big.
>
> This one has about 20k mail accounts.
Aha! Problem probably found! I have had similar problems with large mail
accounts on ext3 partitions. Above some number of files (which I've never
bothered to find out), server load goes through the roof and delivery
slows to a crawl. I suspect you have one or more users with thousands of
files in their maildir -- possibly a postmaster account set to catch-all
(which is dangerous), that is never checked and is full of spam.
Move your maildirs onto a parition formatted with a filesystem better
suited to large numbers of files in directories. Reiserfs is liked by many
and is frequently recommended by others on this list. I use XFS myself,
mainly due to its very nice backup/dump tools.
-Bill
*****************************
Waveform Technology
UNIX Systems Administrator
