From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Zhang Subject: Re: RAID 5 write performance advice Date: Fri, 26 Aug 2005 10:30:21 -0400 Message-ID: <1125066621.5549.27.camel@localhost.localdomain> 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> <430ECA18.10405@web.de> Reply-To: mingz@ele.uri.edu Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <430ECA18.10405@web.de> Sender: linux-raid-owner@vger.kernel.org To: Mirko Benz Cc: Neil Brown , Linux RAID List-Id: linux-raid.ids i would like to suggest u to do a 4+1 raid5 configuration and see what happen. Ming On Fri, 2005-08-26 at 09:51 +0200, Mirko Benz wrote: > 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 >