Sevrin Robstad wrote:
I've tried to increase the cache size - I can't measure any
difference.....
You probably won't help small writes, but large writes will go faster
with a stripe cache of size num_disks*chunk_size*2 or larger.
Raz Ben-Jehuda(caro) wrote:
did u increase the stripe cache size ?
On 1/18/07, Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> 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.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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