Date: Thu, 11 Jun 1998 12:46:54 +0200 From: "Andras Tudos - Computronic, C3" <andras.tudos@computronic.hu> To: "IBS / Andre Oppermann" <andre@pipeline.ch> Cc: isp@FreeBSD.ORG, marci@c3.hu Subject: Re: file system performance Message-ID: <3.0.5.32.19980611124654.00aad210@computronic.hu> In-Reply-To: <357FA86E.96CB3D00@pipeline.ch> References: <3.0.5.32.19980611000210.00a868b0@computronic.hu>
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At 11:50 98.06.11 +0200, IBS / Andre Oppermann wrote: >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). > >Get rid of NFS for incoming mail. NFS IMO does writes syncronously. > But as I pointed out, we see practically NO difference in the performance whether /home is mounted over NFS or used locally. The problem is that there seems to be a upper limit which we reach when we're doing small file copies (actually copying real mail sample taken from /home) to the RAID array. Today we will experiment with fine tuning of the ext. RAID controller (CMD5440). >> Any ideas how to improve performance? > >Let the front-end boxes accept incoming SMTP mail and then use QMQP to >deliver all that stuff to the mailstore box which does local delivery. > It could help, if we could get much better local delivery performance on the backend... >The other point is POP3 access... I think there's no way around NFS but >that should'nt be so problematic since POP3 does only read and delete >which is not so bad over NFS. > Yes, POP3 load is not that bad. The big problem is the periodic huge incoming load caused by user subscriptions to various mailing lists (we have ~60000 mailboxes at the moment and it is linearly growing by ~7500 each month). We have to reach a better peak local delivery performance than the current one to keep the "sitting in the queue" time at an acceptable level. Andras Tudos C3, Budapest To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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