Date: Thu, 11 Jun 1998 11:18:18 -0700 From: Julian Elischer <julian@whistle.com> To: "Andras Tudos - Computronic, C3" <andras.tudos@computronic.hu> Cc: isp@FreeBSD.ORG Subject: Re: file system performance Message-ID: <35801F6A.1CFBAE39@whistle.com> References: <3.0.5.32.19980611000210.00a868b0@computronic.hu>
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Andras Tudos - Computronic, C3 wrote: > > We are setting up a largish qmail based mail server. We are using 3 > frontend machines (PII-233, 128Mb, FreeBSD 2.2.6) to accept incoming smtp > mail and to service pop3 user requests. The mailboxes are on the backend > machine (PII-400, 128Mb, FreeBSD 2.2.6, external HW RAID array on UW SCSI) > and are shared via NFS. All PCs are on a 100Mbps switched LAN. > > The problem: file system performance (either measured over NFS or on the > local RAID array). We can get 1.6Mbps when continuosly copying 1-2K files > and 44Mbps when copying (dd) /dev/zero. The later is perfect, but the > former is too low. We tried almost all options (sync and async mode), but > couldn't get it higher. With this performance the server can deliver about > 700,000 messages per day (measured with simulated mail load), which is less > than required (on long term). > > Any ideas how to improve performance? When there is a trustable snapsot of -current, you should look at usign that, as the new "soft updates" features will make this sort of thing much faster. (this will mainly be of interest for your "future plans" because -current is not really ready yet) The main thing you should do is do profiling of the amount of time spent for each mail item in each part of the system. You may find that you are forking processes in ways that are not needed.. try the following: get a quiet system with KTRACE compiled in the system torn on ktrace for the entire system: cd /var/tmp ktrace -d -i -p 1 -tcnisw send a single mail item to the machine. wait for delivery to complete.. (do NOT log in or do anything else) turn ktrace off ktrace -C (as root) examine the ktrace kdump -R -tcnisw >realdump vi realdump you should from this, get a real undertanding of what it takes to deliver a mail item This will allow you to find out what the real innefficienacies are. > > Andras Tudos > C3, Budapest > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-isp" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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