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Subject: Re: performance issues
From: Brad Knowles (blkskynet.be)
Date: Thu May 18 2000 - 10:50:50 CDT

At 7:20 PM +0200 2000/5/17, Brad Knowles wrote:

> 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.

        I'm just doing some benchmarking now. You wouldn't *believe* how
much of a difference this single change can make. All these tests
are run on a Sun E250 with dual 248Mhz CPUs, 1GB RAM, mirrored 9GB
Seagate Cheetah system disk for all filesystems except
/var/spool/mqueues (no UFS logging), and /var/spool/mqueues on a
separate 18GB Seagate Cheetah disk.

        Before (no UFS logging):

                /usr/bin/time ./smtp-source -m1000 -s20 -l15360 -c
-tnulllocalhost localhost
                1000

                real 50.2
                user 1.2
                sys 3.8

        That works out to 19.920 messages per second.

        After (with UFS logging):

                /usr/bin/time ./smtp-source -m1000 -s20 -l15360 -c
-tnulllocalhost localhost
                1000

                real 18.7
                user 1.3
                sys 2.5

        That works out to 53.475 messages per second.

        The first numbers there are about as good as I get on our
existing outbound mail relay servers (Sun Ultra5s with 256MB RAM, one
250Mhz or 330Mhz processor, a single 4GB or 9GB IDE drive, and UFS
logging on the /var/spool/mqueues partition). The second set of
numbers are higher than I've seen before, but I'm not done yet. ;-)

        I'm also going to try mirroring /var/spool/mqueues to see how
much that slows things down (with and without UFS logging), as well
as striping it (with and without UFS logging). I expect to see these
numbers above 100 messages/second before I'm done.... 

--
   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