Date: Mon, 30 Oct 2006 07:11:29 +0200 From: Petri Helenius <pete@he.iki.fi> To: Greg 'groggy' Lehey <grog@FreeBSD.org> Cc: Steve Peterson <stevep-hv@zpfe.com>, performance@freebsd.org Subject: Re: gvinum raid5 performance seems slow Message-ID: <45458981.8010302@he.iki.fi> In-Reply-To: <20061030013211.GC1052@wantadilla.lemis.com> References: <6.2.3.4.0.20061027180329.020bed68@localhost> <4542D941.2070204@centtech.com> <6.2.3.4.0.20061028124559.02105930@localhost> <4543AD35.30205@he.iki.fi> <20061030013211.GC1052@wantadilla.lemis.com>
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Greg 'groggy' Lehey wrote: > > Single stream tests aren't very good examples for RAID-5, because it > performs writes in two steps: first it reads the old data, then it > writes the new data. > If it really does it this way, instead doing write-only when writing sufficiently large blocks, that would explain the performance due to double rotational latency wait for each stripe size. Most implementations also use read/write caches to optimize this even further. Pete
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