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Replies:
3
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Last Post:
Nov 3, 2009 7:14 AM
by: mschenck
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Posts:
1
From:
Registered:
10/15/09
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approximately resilver time
Posted:
Oct 19, 2009 10:24 PM
To: Communities » storage » discuss
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Thinking about ZFS storage. I wish to know, that to expect.
What approximately resilver time after disk failure on 8+2 raidz2. Disks is 7200 SATA 1Tb. 2Tb will be interesting too.
Let's assume host is powerful enough and in idle state.
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Posts:
719
From:
US
Registered:
8/19/08
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Re: [storage-discuss] approximately resilver time
Posted:
Oct 20, 2009 8:17 AM
in response to: borov
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On Mon, 19 Oct 2009, borov wrote:
> Thinking about ZFS storage. I wish to know, that to expect.
> What approximately resilver time after disk failure on 8+2 raidz2.
> Disks is 7200 SATA 1Tb. 2Tb will be interesting too.
The resilver time depends on how much data there is to be resilvered,
the typical file sizes, filesystem blocksize, and the degree of
fragmentation. It also depends on the sequential read rate from each
disk, as well as average seek time. The resilver time then depends on
the average data rate during resilvering (for your hardware) and the
amount of data to be resilvered.
This is the math I used in 'bc' for 20MB/second and 1TB to be
resilvered:
% bc
scale=2
((1000*1000*1000*1000)/(20*1000*1000))/(60*60)
13.88
So we get these results:
Resilver Rate Hours
20MB/second 13.88
30MB/second: 9.25
40MB/second: 6.94
50MB/second: 5.55
60MB/second: 4.62
70MB/second: 3.96
80MB/second: 3.47
You may want to search the zfs-discuss list for reports of typical
resilver rates. From what I have seen posted by others, resilver
rates for raidz2 with SATA disks tend to be low.
Bob
--
Bob Friesenhahn
bfriesen at simple dot dallas dot tx dot us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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Posts:
8
From:
US
Registered:
10/5/09
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Re: [storage-discuss] approximately resilver time
Posted:
Oct 20, 2009 9:09 AM
in response to: bfriesen
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Bob Friesenhahn wrote:
> Resilver Rate Hours
> 20MB/second 13.88
> 30MB/second: 9.25
> 40MB/second: 6.94
> 50MB/second: 5.55
> 60MB/second: 4.62
> 70MB/second: 3.96
> 80MB/second: 3.47
>
> You may want to search the zfs-discuss list for reports of typical
> resilver rates. From what I have seen posted by others, resilver rates
> for raidz2 with SATA disks tend to be low.
Here's a recent data point. Yesterday one of my systems had checksum errors on
one disk, and the hot spare was resilvered in. The pool is a 13-way raidz2 with
one hot spare, all 2TB SATA (Western Digital WD2002FYPS) across 2 8-port
Supermicro AOC-SAT2-MV8 controllers.
The pool contains about 4TB of data, and the resilvered disk got 317GB of that.
It took 4 hours and 47 minutes to resilver, so that works out to about
19MB/sec. The system continued to function while the resilver proceeded-- it's
a backup server, so most of the I/O was sequential write, but it was very bursty
as individual clients were backed up throughout the day.
Regards,
Eric
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Posts:
9
From:
US
Registered:
9/30/05
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Re: [storage-discuss] approximately resilver time
Posted:
Nov 3, 2009 7:14 AM
in response to: esproul
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Is there any word on the possible feature add of giving higher
priority to resilver of a zpool for maintenance windows in order to
expedite resilvering?
Best regards,
Michael Schenck
On Tue, Oct 20, 2009 at 11:09 AM, Eric Sproul <esproul at omniti dot com> wrote:
> Bob Friesenhahn wrote:
>> Resilver Rate Hours
>> 20MB/second 13.88
>> 30MB/second: 9.25
>> 40MB/second: 6.94
>> 50MB/second: 5.55
>> 60MB/second: 4.62
>> 70MB/second: 3.96
>> 80MB/second: 3.47
>>
>> You may want to search the zfs-discuss list for reports of typical
>> resilver rates. From what I have seen posted by others, resilver rates
>> for raidz2 with SATA disks tend to be low.
>
> Here's a recent data point. Yesterday one of my systems had checksum errors on
> one disk, and the hot spare was resilvered in. The pool is a 13-way raidz2 with
> one hot spare, all 2TB SATA (Western Digital WD2002FYPS) across 2 8-port
> Supermicro AOC-SAT2-MV8 controllers.
>
> The pool contains about 4TB of data, and the resilvered disk got 317GB of that.
> It took 4 hours and 47 minutes to resilver, so that works out to about
> 19MB/sec. The system continued to function while the resilver proceeded-- it's
> a backup server, so most of the I/O was sequential write, but it was very bursty
> as individual clients were backed up throughout the day.
>
> Regards,
> Eric
> _______________________________________________
> storage-discuss mailing list
> storage-discuss at opensolaris dot org
> http://mail.opensolaris.org/mailman/listinfo/storage-discuss
>
--
Michael Schenck - www.tek-ops.com
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