From: Mirko Benz <mirko.benz@web.de>
To: mingz@ele.uri.edu
Cc: Neil Brown <neilb@cse.unsw.edu.au>,
Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: RAID 5 write performance advice
Date: Fri, 26 Aug 2005 17:29:41 +0200 [thread overview]
Message-ID: <430F3565.2070302@web.de> (raw)
In-Reply-To: <1125066621.5549.27.camel@localhost.localdomain>
Hello,
Here are the results using 5 disks for RAID 5 – basically the same
results but with lower values.
Again, much slower than it could be.
*** dd TEST ***
time dd if=/dev/zero of=/dev/md0 bs=1M
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 of
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:
>
>
>>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
>>
>>
>>
>
>
>
>
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next prev parent reply other threads:[~2005-08-26 15:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-24 8:24 RAID 5 write performance advice Mirko Benz
2005-08-24 12:46 ` Ming Zhang
2005-08-24 13:43 ` Mirko Benz
2005-08-24 13:49 ` Ming Zhang
2005-08-24 21:32 ` Neil Brown
2005-08-25 16:38 ` Mirko Benz
2005-08-25 16:54 ` Ming Zhang
2005-08-26 7:51 ` Mirko Benz
2005-08-26 14:26 ` Ming Zhang
2005-08-26 14:30 ` Ming Zhang
2005-08-26 15:29 ` Mirko Benz [this message]
2005-08-26 17:05 ` Ming Zhang
2005-08-28 23:28 ` Neil Brown
2005-09-01 19:44 ` djani22
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