[zfs-discuss] raidz1 or raidz2

Christ Schlacta aarcane at aarcane.org
Fri Nov 2 13:09:18 EDT 2012


Gordan, I was under the impression that resilver time scaled with disk
size, and not count. The 4 day period should be the same on any raid zn
configuration he chooses
On Nov 2, 2012 10:01 AM, "Gordan Bobic" <gordan.bobic at gmail.com> wrote:

> On 11/02/2012 04:34 PM, Brian Menges wrote:
>
>> Recalling an older post:
>> http://mail.opensolaris.org/**pipermail/zfs-discuss/2010-**
>> September/044701.html<http://mail.opensolaris.org/pipermail/zfs-discuss/2010-September/044701.html>
>>
>> SNIP ---
>> RAIDZ2 vdevs should have 4, 6, or 10 devices in each vdev
>> RAIDZ3 vdevs should have 5, 7, or 11 devices in each vdev
>> SNIP ---
>>
>> My recommendation would be to use RaidZ2 with 10 devices per vdev; this
>> fits nicely with 60 disks assuming that they're all for the pool. Given
>> they're 3tb disks, I'd strongly suggest RaidZ2 over RaidZ1 for previously
>> noted reasons - reslivering will murder this array. RaidZ3 is appealing,
>> but you're going to have to declare some spares at that point (and by
>> declaring spares, I mean leave them alone - blank non-allocated devs since
>> spares are still broken in rc11 to my knowledge). In a RaidZ3 I'd suggest 7
>> devices per vdev, times 8 means you'd use 56 drives, you'll have 4 spares
>> available.
>>
>> Recap
>>
>> Raidz2 - 10 devices per vdev, 6 vdevs
>> Raidz3 - 7 devices per vdev, 8 vdevs, 4 remaining devices as "spares"
>>
>
> (8+2)x3TB is pushing your luck, IMO. You are looking at resilvering time
> of about 4-5 days. I wouldn't use more than 4+2 with disks that are so
> large.
>
> Gordan
>
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