Date: Tue, 19 Oct 2004 17:18:26 -0400 From: Bill Vermillion <bv@wjv.com> To: Kristofer Pettijohn <krishopper@cybernetik.net> Cc: freebsd-isp@freebsd.org Subject: Re: Disk I/O Performance with CCD Message-ID: <20041019211826.GB55676@wjv.com> In-Reply-To: <20041019192252.GB78974@cybernetik.net> References: <20041019192252.GB78974@cybernetik.net>
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Ashes to ashes, and DOS to DOS Kristofer Pettijohn was heard to say on or about Tue, Oct 19, 2004 at 14:22 : > Im looking for some suggestions on I/O performance. > I'm using FreeBSD 4.10-RELEASE on a Usenet transit server running > Diablo for the transit software. > I have 4 Seagate ST373435LC SCSI drives, 70GB each, and I am using > CCD to bind them together with RAID-0 stripes. > I can pull in anywhere from 30-40 MB sec and push out ~ 8-15 MB/sec.. > averaging about 50 MB/sec throughput.. feeds coming in are coming > in just fine, but sending stuff back out is lagging behind.. its > falling about a half hour behind every hour. > > I've used tunefs to set the average file size to 20 MB and enabled > soft-updates, as these are generally larger binary files that just > get appended to, and then seeked later on to send the article out, > I've played with setting the stripe size from anywhere between 8MB > and 64MB, and did not see much change on performance between those. > > Maybe I'm just missing something small, but on these SCSI drives > which have 160 MB/s transfer rates, I'm expecting a bit more than > I'm getting with CCD. > Can someone give me any pointers to look at or suggestions of things > to try? Why not run one of the benchmarks to see what your disk I/O looks like through the filesystem. I've been using the old Iozone 2.1 for about 10 years - it's simple and only tests throught through the filesystem. I save a copy of the output when I first install a system and then if things appear slow later I'll run it again to see if it did slow down or that I remembered the speeds differently. It's under /usr/ports/benchmarks/iozone21. Bill -- Bill Vermillion - bv @ wjv . com
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