From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brendan Conoboy Subject: Re: 2x6 or 3x4 raid10 arrays ? Date: Thu, 28 Feb 2008 14:04:52 -0700 Message-ID: <47C721F4.1080506@redhat.com> References: <1204195554.16924.16.camel@franck-gusty> <20080228192500.4d9110d9@absurd> <20080228215339.6674f29d@absurd> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080228215339.6674f29d@absurd> Sender: linux-raid-owner@vger.kernel.org To: Janek Kozicki Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Janek Kozicki wrote: > * two 6 disks raid10 arrays : theoretical max speed 6 times single disc > * three 4 disks raid10 arrays : theoretical max speed 4 times single disc > * single raid10 far=2 : theoretical max speed 12 times single disc (!) > > isn't that true? If speed is raw throughput then that's approximately right. Unless you're streaming huge piles of data, that sort of speed isn't what you need to tune for, though. Look at it this way: two 6 disk raid 10 arrays : theoretical max seeks per operation: 6 times the seeks of a single disk three 4 disk raid 10 arrays: theoretical max seeks per operation: 4 times the seeks of a single disk one 12 disk raid 10 arrays: theoretical max seeks per operation: 12 times the seeks of a single disk! Seeks are bad. You have to tune for your workload. -- Brendan Conoboy / Red Hat, Inc. / blc@redhat.com