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Subject: Re: performance issues
From: Brad Knowles (blkskynet.be)
Date: Wed May 17 2000 - 12:20:53 CDT

At 10:05 AM -0400 2000/5/17, Adam Levin wrote:

> The questions are: any thoughts as to why it slowed down again? Anything
> bad about having 200 qmgr, 50 defer, 50 bounce and 50 cleanups, assuming
> the system isn't going into anaphylactic shock? Anything else I should be
> considering on a server that once a week will be hit with an outgoing
> mailing in the tens and possibly hundreds of thousands, as well as having
> to handle regular office mail of a few thousand per day? We have about
> 100 users who use MSOutlook to POP mail off.

        You haven't shown us your postfix configuration. In particular,
you haven't shown us the values of qmgr_message_active_limit,
qmgr_site_hog_factor, hash_queue_depth, hash_queue_names, etc....
Let us see the output of `postconf -n` for your system.

        You really want to hash your incoming and deferred directories,
if you ever expect that there is an outside chance that you might
have more than ~1000 messages in your queue at any one time -- any
more than that, and you start seeing significant effects of directory
access times, etc.... A hash_queue_depth of two will let you handle
~1000 messages per directory times 16 * 16 directories, for a total
of 256,000 messages.

        If you boost your qmgr_message_active_limit beyond 1000, you may
also want to hash the active directory, although sadly it will also
have to share a level of hashed directories with all the other hashed
directories, and this will probably slow it down somewhat (but not as
much as not hashing it at all).

        Also, you want to make sure that you're doing at least UFS
Logging on the mqueue partition that postfix runs on. Ideally, you'd
run Veritas VxFS or something even more intelligent with regards to
the writing of synchronous meta-data, but even just simple UFS
Logging should help somewhat. 

--
   These are my opinions -- not to be taken as official Skynet policy
======================================================================
Brad Knowles, <blkskynet.be>                || Belgacom Skynet SA/NV
Systems Architect, Mail/News/FTP/Proxy Admin || Rue Colonel Bourg, 124
Phone/Fax: +32-2-706.13.11/12.49             || B-1140 Brussels
http://www.skynet.be                         || Belgium