Date: Thu, 23 Oct 2008 10:59:45 -0700 From: Chuck Swiger <cswiger@mac.com> To: Stephen Sanders <ssanders@softhammer.net> Cc: freebsd-performance@freebsd.org Subject: Re: Disk Throughput test Message-ID: <B262AED3-0A62-429C-B9D1-7FADB853DE37@mac.com> In-Reply-To: <4900B94B.5000108@softhammer.net> References: <490097CC.9010802@opnet.com> <A0D72207-41DF-444A-8911-22EFCB5D747C@mac.com> <4900B94B.5000108@softhammer.net>
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On Oct 23, 2008, at 10:50 AM, Stephen Sanders wrote: > Good point about the RAID. It is set for RAID 5 as the data is > supposed > to be protected. RAID-10 provides somewhat better data protection, but less available space and better write performance especially for small writes. (For big writes, RAID-5 can do OK also, but small writes tend to really degrade RAID-5 performance, down to an order of magnitude *less* throughput compared with a single raw drive.) > Interestingly enough, diskinfo is telling me that the drive throughput > is 175MB/s. I'm guessing that this means diskinfo is a mixture of > reads > and writes? No, it should only be doing reads. For best-case read performance, it's likely to be at or near: dd if=_your_disks_ of=/dev/null bs=_raid_stripe_size_ ...or adjust bs up or down by factors of 2 and benchmark. Regards, -- -Chuck
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