From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keld =?iso-8859-1?Q?J=F8rn?= Simonsen Subject: Re: mdadm raid10 performance Date: Mon, 2 Jun 2008 12:26:19 +0200 Message-ID: <20080602102619.GA30779@rap.rap.dk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: ???? ????????? Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Mon, Jun 02, 2008 at 02:47:53AM +0600, ???? ????????? wrote: > Hello. I have a simple question. > > I just created mdadm raid10 with four disks. The raid build process > complete successfully. > All of 4 HDD are connected with separate SATA wires directly to motherboard. > The mode of operation (selected in bios) neither AHCI nor RAID. > > I decide to acheive performance information of software RAID. > So I read 10 blocks by 64Mb. This give me roughly performance of one disk. > (I expect that it will be 4x speed ! it should read from 4 hdd > simultaneously!!!, BUT NOT! ) > > So, second test were reading 10 blocks (from 0 to 9) in one process, > and 10 blocks (from 10 to 19) in second thread. > I acheive performance of half disk... in each thread. > > WTF? maybe raid is configured incorrectly ? Or my tests are invalid ? > > Any ideas ? have a look on the howto performance section. http://linux-raid.osdl.org/index.php/Performance the far layout is "far" better:-) Also note the problem solving section there. doing IO in more threads will have your array behave in random read mode. What kernel are you running? best regards keld