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 17:29:41 +0200 Message-ID: <430F3565.2070302@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> <430ECA18.10405@web.de> <1125066621.5549.27.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1125066621.5549.27.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, Here are the results using 5 disks for RAID 5 =E2=80=93 basically the s= ame=20 results but with lower values. Again, much slower than it could be. *** dd TEST *** time dd if=3D/dev/zero of=3D/dev/md0 bs=3D1M 2819620864 bytes transferred in 23,410720 seconds (120441442 bytes/sec) iostat 5 output: avg-cpu: %user %nice %sys %iowait %idle 0,10 0,00 55,40 36,20 8,30 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 345,09 1999,20 71501,40 9976 356792 sdc 348,10 2412,83 71434,07 12040 356456 sdd 356,31 2460,92 71748,30 12280 358024 sde 351,50 2456,11 71058,92 12256 354584 sdf 348,10 2008,82 70935,47 10024 353968 sdg 0,00 0,00 0,00 0 0 sdh 0,00 0,00 0,00 0 0 sdi 0,00 0,00 0,00 0 0 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 35226,65 0,00 281813,23 0 1406248 disktest gives 99 MB/s but shows the same behaviour (unbalanced usage o= f=20 disks). Regards, Mirko Ming Zhang schrieb: >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: > =20 > >>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] s= db[0] >> 1250326528 blocks 64k chunks >> >>*** dd TEST *** >> >>time dd if=3D/dev/zero of=3D/dev/md0 bs=3D1M >>14967373824 bytes transferred in 32,060497 seconds (466847843 bytes/s= ec) >> >>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_wrt= n >>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 58163= 2 >>sdc 455,51 0,00 116540,28 0 58153= 6 >>sdd 450,10 0,00 116545,09 0 58156= 0 >>sde 454,11 0,00 116559,52 0 58163= 2 >>sdf 452,30 0,00 116559,52 0 58163= 2 >>sdg 454,71 0,00 116553,11 0 58160= 0 >>sdh 453,31 0,00 116533,87 0 58150= 4 >>sdi 453,91 0,00 116556,31 0 58161= 6 >>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 46529= 20 >> >>Comments: 466 MB / 8 =3D 58,25 MB/s which is about the same as a dd t= o a=20 >>single disk (58,5 MB/s). So the controller + I/O subsystem is not the= =20 >>bottleneck. >> >>Regards, >>Mirko >> >> =20 >> > > > =20 > - To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html