From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: Performance question Date: Sat, 17 Jan 2009 13:37:57 -0500 Message-ID: <49722585.4020400@tmr.com> References: <20090117171806.GA9432@lazy.lzy> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090117171806.GA9432@lazy.lzy> Sender: linux-raid-owner@vger.kernel.org To: Piergiorgio Sartor Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Piergiorgio Sartor wrote: > Hi all, > > I'll have to setup some machines with two HDs (each) > in order to get some redundancy. > > Reading the MD features I noticed there are several > possibilities to create a mirror. > I was wondering which one offer the best perfomances > and/or what are the compromises to accept between > the different solutions. > > One possibility is a classic RAID-1 mirror. > Another is a RAID-10 far. > There would also be the RAID-10 near, but I guess > this is equivalent to RAID-1. > > Any suggestion on which method offers higher "speed"? > Or there are other possibilities with 2 HDs (keeping > the redundancy, of course)? > Mirrored array will offer slower write speed no matter how you do it, usually about the speed of a single drive. With raid10 far you should get about N times faster read than a single drive, where N is drives in the array. Clearly using three or more drives will help a LOT in typical performance. -- Bill Davidsen "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark