From: NeilBrown <neilb@suse.de>
To: Pol Hallen <raid1@fuckaround.org>
Cc: Linux-RAID <linux-raid@vger.kernel.org>
Subject: Re: Performarce raid6 degraded
Date: Sat, 21 May 2011 22:37:23 +1000 [thread overview]
Message-ID: <20110521223723.7d2f5f1a@notabene.brown> (raw)
In-Reply-To: <201105211316.18565.raid1@fuckaround.org>
On Sat, 21 May 2011 13:16:18 +0200 Pol Hallen <raid1@fuckaround.org> 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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next prev parent reply other threads:[~2011-05-21 12:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-21 11:16 Performarce raid6 degraded Pol Hallen
2011-05-21 12:37 ` NeilBrown [this message]
-- strict thread matches above, loose matches on Subject: below --
2011-05-22 12:57 Pol Hallen
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