[CentOS] RAID 5 setup?
Benjamin Franz
jfranz at freerun.com
Sat Mar 27 13:24:32 UTC 2010
Chan Chung Hang Christopher wrote:
> Benjamin Franz wrote:
>
>> Yup. 8 way RAID1 for the OS, 8 way RAID6 for the data. I was hoping when
>> I setup the 8-way RAID1 for the OS that I would get really good read
>> speeds since md is supposed to stripe reads from RAID1, but in practice
>> the RAID6 completely kills it for read performance (~61 MB/sec from the
>> RAID1 partition vs ~200 MB/sec from the RAID6 partition).
>>
>
> What are you running? I think there was a patch that evened out the
> reads across all members as it would at times solely read from one and
> then another...
>
>
I'm running fully up-to-date CentOS 5.4, kernel 2.6.18-164.15.1. The
test was done with a default run of bonnie++. Watching the disk I/O
while it ran suggested that it was only using some of the disks at a
time to read (but changing which ones every few seconds).
8 x RAID1
Version 1.96 ------Sequential Output------ --Sequential Input-
--Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
pbox16.freerun. 16G 586 95 17263 5 13016 1 2263 97 60793 3
644.2 4
Latency 203ms 188s 1521ms 14714us 557ms
1265ms
Version 1.96 ------Sequential Create------ --------Random
Create--------
pbox16 -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
/sec %CP
16 12418 16 +++++ +++ 10999 12 27730 34 +++++ +++
29916 32
Latency 109us 638us 681us 200us 25us
39us
8 x RAID6
Version 1.96 ------Sequential Output------ --Sequential Input-
--Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
pbox16.freerun. 16G 611 96 90060 15 55711 14 2407 96 200901 27
522.3 15
Latency 13157us 604ms 1727ms 32420us 142ms
73131us
Version 1.96 ------Sequential Create------ --------Random
Create--------
pbox16 -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
/sec %CP
16 10298 16 +++++ +++ 24208 32 30395 45 +++++ +++
32511 43
Latency 18504us 598us 613us 87us 25us
121us
1.96,1.96,pbox16,1,1269604576,16G,,611,96,90060,15,55711,14,2407,96,200901,27,522.3,15,16,,,,,10298,16,+++++,+++,24208,32,30395,45,+++++,+++,32511,43,13157us,604ms,1727ms,32420us,142ms,73131us,18504us,598us,613us,87us,25us,121us
--
Benjamin Franz
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