From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mirko Benz Subject: Re: RAID 5 write performance advice Date: Fri, 26 Aug 2005 09:51:52 +0200 Message-ID: <430ECA18.10405@web.de> References: <430C2EA6.2050103@web.de> <1124887589.5550.27.camel@localhost.localdomain> <430C798B.1030107@web.de> <17164.59261.540591.841830@cse.unsw.edu.au> <430DF416.1070101@web.de> <1124988876.5552.59.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1124988876.5552.59.camel@localhost.localdomain> Sender: linux-raid-owner@vger.kernel.org To: mingz@ele.uri.edu Cc: Neil Brown , Linux RAID List-Id: linux-raid.ids Hello, We have created a RAID 0 for the same environment: Personalities : [raid0] [raid5] md0 : active raid0 sdi[7] sdh[6] sdg[5] sdf[4] sde[3] sdd[2] sdc[1] sdb[0] 1250326528 blocks 64k chunks *** dd TEST *** time dd if=/dev/zero of=/dev/md0 bs=1M 14967373824 bytes transferred in 32,060497 seconds (466847843 bytes/sec) iostat 5 output: avg-cpu: %user %nice %sys %iowait %idle 0,00 0,00 89,60 9,50 0,90 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn hda 0,00 0,00 0,00 0 0 sda 0,00 0,00 0,00 0 0 sdb 455,31 0,00 116559,52 0 581632 sdc 455,51 0,00 116540,28 0 581536 sdd 450,10 0,00 116545,09 0 581560 sde 454,11 0,00 116559,52 0 581632 sdf 452,30 0,00 116559,52 0 581632 sdg 454,71 0,00 116553,11 0 581600 sdh 453,31 0,00 116533,87 0 581504 sdi 453,91 0,00 116556,31 0 581616 sdj 0,00 0,00 0,00 0 0 sdk 0,00 0,00 0,00 0 0 sdl 0,00 0,00 0,00 0 0 sdm 0,00 0,00 0,00 0 0 sdn 0,00 0,00 0,00 0 0 md0 116556,11 0,00 932448,90 0 4652920 Comments: 466 MB / 8 = 58,25 MB/s which is about the same as a dd to a single disk (58,5 MB/s). So the controller + I/O subsystem is not the bottleneck. Regards, Mirko