Date: Sun, 30 Mar 2003 16:49:23 -0700 From: "Jan L. Peterson" <jlp@peterson.ath.cx> To: freebsd-stable@freebsd.org Subject: Re: vinum performance Message-ID: <20030330234923.44B8DC5303@aurora.peterson.ath.cx> In-Reply-To: Message from Chuck Swiger <cswiger@mac.com> of "Sun, 30 Mar 2003 12:01:17 EST." <3E8722DD.5050703@mac.com>
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Just to shed some real-world light on this vinum benchmark discussion. At a previous employer we had a few HP systems with hardware RAID boards on them (AMI MegaRaid compatible boards, but some HP part number... I can't remember exactly which). On one system, which was in support of our web site (it stored thousands of small files containing html text that would be referenced in pretty much random order), we configured an HP RS12 (JBOD with 12 disks in it) on the AMI controller as a RAID 5 volume. Performance was excellent (this disk supported mostly reads... once a collection of files had been uploaded, it was not modified). Much better then with the files on local disk, even. On another system, where these files were created before being uploaded, performance with RAID 5 was abysmal. We ended up yanking the AMI controller and using the on-board Symbios controller and using vinum as RAID 0+1 (stripe each group of six disks, mirror one group to the other group, each group on a separate physical controller -- the Sym board had dual channels). With this setup, performance was much better. So the upshot is, if you're doing a lot of writes, don't use RAID 5. If you're doing a lot of reads, and you have hardware RAID 5 available, it's probably a win. -jan- -- Jan L. Peterson <jlp@softhome.net> If your company is looking for a SAGE level IV, let me know.
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