Performarce raid6 degraded

Hi folks, after fail of a disk on my raid6 sw I check with dd the performance
of raid:

dd if=/dev/zero of=degradedraid bs=1000024 count=100
100+0 records in
100+0 records out
100002400 bytes (100 MB) copied, 288.254 s, 347 kB/s

is it correct? only 347Kb/s on a raid6 degraded?

mdadm --detail /dev/md0
/dev/md0:
Version : 0.90
Creation Time : Mon Sep 27 14:19:15 2010
Raid Level : raid6
Array Size : 5860543744 (5589.05 GiB 6001.20 GB)
Used Dev Size : 1465135936 (1397.26 GiB 1500.30 GB)
Raid Devices : 6
Total Devices : 7
Preferred Minor : 0
Persistence : Superblock is persistent

Update Time : Sat May 21 13:14:43 2011
State : active, degraded
Active Devices : 5
Working Devices : 5
Failed Devices : 2
Spare Devices : 0

Layout : left-symmetric
Chunk Size : 64K

UUID : 9bd6372e:e2eab1d5:d2bdc3cb:ad12f41d
Events : 0.385693

Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1
2 0 0 2 removed
3 8 81 3 active sync /dev/sdf1
4 8 65 4 active sync /dev/sde1
5 8 49 5 active sync /dev/sdd1

6 8 145 - faulty spare
7 8 33 - faulty spare

thanks!

Pol
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Re: Performarce raid6 degraded

On Sat, 21 May 2011 13:16:18 +0200 Pol Hallen wrote:

> Hi folks, after fail of a disk on my raid6 sw I check with dd the performance
> of raid:
>
> dd if=/dev/zero of=degradedraid bs=1000024 count=100
> 100+0 records in
> 100+0 records out
> 100002400 bytes (100 MB) copied, 288.254 s, 347 kB/s
>
> is it correct? only 347Kb/s on a raid6 degraded?

What was it when the array was not degraded?

1000024 is a rather strange block size to use. Try a power of 2 and see if
it makes a difference.

I would expect large sequential writes to go at much the same speed as
non-degraded, but smaller or non-aligned writes could certainly go more
slowly - maybe half speed at a guess.

NeilBrown


>
> mdadm --detail /dev/md0
> /dev/md0:
> Version : 0.90
> Creation Time : Mon Sep 27 14:19:15 2010
> Raid Level : raid6
> Array Size : 5860543744 (5589.05 GiB 6001.20 GB)
> Used Dev Size : 1465135936 (1397.26 GiB 1500.30 GB)
> Raid Devices : 6
> Total Devices : 7
> Preferred Minor : 0
> Persistence : Superblock is persistent
>
> Update Time : Sat May 21 13:14:43 2011
> State : active, degraded
> Active Devices : 5
> Working Devices : 5
> Failed Devices : 2
> Spare Devices : 0
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> UUID : 9bd6372e:e2eab1d5:d2bdc3cb:ad12f41d
> Events : 0.385693
>
> Number Major Minor RaidDevice State
> 0 8 1 0 active sync /dev/sda1
> 1 8 17 1 active sync /dev/sdb1
> 2 0 0 2 removed
> 3 8 81 3 active sync /dev/sdf1
> 4 8 65 4 active sync /dev/sde1
> 5 8 49 5 active sync /dev/sdd1
>
> 6 8 145 - faulty spare
> 7 8 33 - faulty spare
>
> thanks!
>
> Pol
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> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html

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Re: Performarce raid6 degraded

> What was it when the array was not degraded?

ehm.. I never didn't wrote the results :-O

I discover another bad disk.. problems problems..

thanks :-)

Pol
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