Re: bad performance on RAID 5

[Sevrin Robstad <quackyo@start.no>]

I've tried to increase the cache size - I can't measure any difference.....

Raz Ben-Jehuda(caro) wrote:
> did u  increase the stripe cache size ?
>
>
> On 1/18/07, Justin Piszcz <jpiszcz@lucidpixels.com> wrote:
>> Sevrin Robstad wrote:
>> > I'm suffering from bad performance on my RAID5.
>> >
>> > a "echo check >/sys/block/md0/md/sync_action"
>> >
>> > gives a speed at only about 5000K/sec , and HIGH load average :
>> >
>> > # uptime
>> > 20:03:55 up 8 days, 19:55,  1 user,  load average: 11.70, 4.04, 1.52
>> >
>> > kernel is 2.6.18.1.2257.fc5
>> > mdadm is v2.5.5
>> >
>> > the system consist of an athlon XP1,2GHz and two Sil3114 4port S-ATA
>> > PCI cards with a total of 6  250gb S-ATA drives connected.
>> >
>> > [root@compaq ~]# mdadm --detail /dev/md0
>> > /dev/md0:
>> >        Version : 00.90.03
>> >  Creation Time : Tue Dec  5 00:33:01 2006
>> >     Raid Level : raid5
>> >     Array Size : 1218931200 (1162.46 GiB 1248.19 GB)
>> >    Device Size : 243786240 (232.49 GiB 249.64 GB)
>> >   Raid Devices : 6
>> >  Total Devices : 6
>> > Preferred Minor : 0
>> >    Persistence : Superblock is persistent
>> >
>> >    Update Time : Wed Jan 17 23:14:39 2007
>> >          State : clean
>> > Active Devices : 6
>> > Working Devices : 6
>> > Failed Devices : 0
>> >  Spare Devices : 0
>> >
>> >         Layout : left-symmetric
>> >     Chunk Size : 256K
>> >
>> >           UUID : 27dce477:6f45d11b:77377d08:732fa0e6
>> >         Events : 0.58
>> >
>> >    Number   Major   Minor   RaidDevice State
>> >       0       8        1        0      active sync   /dev/sda1
>> >       1       8       17        1      active sync   /dev/sdb1
>> >       2       8       33        2      active sync   /dev/sdc1
>> >       3       8       49        3      active sync   /dev/sdd1
>> >       4       8       65        4      active sync   /dev/sde1
>> >       5       8       81        5      active sync   /dev/sdf1
>> > [root@compaq ~]#
>> >
>> >
>> > Sevrin
>> > -
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>>
>> If they are on the PCI bus, that is about right, you probably should be
>> getting 10-15MB/s, but it is about right.  If you had each drive on its
>> own PCI-e controller, then you would get much faster speeds.
>>
>> -
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>
>