zfs discuss - Jan 2011 - Migrating zpool to new drives with 4K Sectors

Hi ZFS Discuss,

I have a 8x 1TB RAIDZ running on Samsung 1TB 5400rpm drives with 512b sectors.

I will be replacing all of these with 8x Western Digital 2TB drives
with support for 4K sectors.  The replacement plan will be to swap out
each of the 8 drives until all are replaced and the new size (~16TB)
is available with a `zfs scrub`.

My question is, how do I do this and also factor in the new 4k sector
size?  or should I find a 2TB drive that still uses 512b sectors?


Thanks

zfs replace will copy across on to the disk with the same old ashift=9,
whereas you want ashift=12 for 4KB drives. (size = 2^ashift)

You''d need to make a new pool (or add a vdev to an existing pool) with
the
modified tools in order to get proper performance out of 4KB drives.

On 7 January 2011 17:43, Matthew Angelo <bangers at gmail.com> wrote:
> Hi ZFS Discuss,
>
> I have a 8x 1TB RAIDZ running on Samsung 1TB 5400rpm drives with 512b
> sectors.
>
> I will be replacing all of these with 8x Western Digital 2TB drives
> with support for 4K sectors.  The replacement plan will be to swap out
> each of the 8 drives until all are replaced and the new size (~16TB)
> is available with a `zfs scrub`.
>
> My question is, how do I do this and also factor in the new 4k sector
> size?  or should I find a 2TB drive that still uses 512b sectors?
>
>
> Thanks
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>
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I have recently done this. See here for more details:

http://www.solarismen.de/archives/5-Solaris-and-the-new-4K-Sector-Disks-e.g.-WDxxEARS-Part-2.html)

What version are you running?

There''s a compiled version of the modified zpool command that will
create pools that are 4K aligned somewhere, for OpenIndiana snv_147 & zpool
28 I think. I have also compiled an OpenSolaris snv_134 & zpool 22 version.
If you want it I can send it to you.
-- 
This message posted from opensolaris.org

Hi Benji,

I did take a read of your blog before posting this.   But it didn''t
have the exact answer I was looking for.  OS Version is Solaris 10 U9
x86.  Your blog was highly informative, but didn''t say if you can zfs
replace into a 4kb drive - it was more discussing the ability to
detect the WD drives as 4kb during a zpool create/

I was hoping to do this without creating a new device, although I can
understand the technical reason why this isn''t possible.

Thanks




On Sat, Jan 8, 2011 at 12:33 AM, Benji <b.robichaud at gmail.com>
wrote:
> I have recently done this. See here for more details:
>
>
http://www.solarismen.de/archives/5-Solaris-and-the-new-4K-Sector-Disks-e.g.-WDxxEARS-Part-2.html)
>
> What version are you running?
>
> There''s a compiled version of the modified zpool command that will
create pools that are 4K aligned somewhere, for OpenIndiana snv_147 & zpool
28 I think. I have also compiled an OpenSolaris snv_134 & zpool 22 version.
If you want it I can send it to you.
> --
> This message posted from opensolaris.org
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

Actually, it is not my blog ;)

To answer your question: you first need to create a new vdev that is 4K aligned
unfortunately. I am not aware of any other means to accomplish what you seek.
-- 
This message posted from opensolaris.org

Except for meta data which seems to be written in small pieces,
wouldn''t having a zfs record size being a multiple of 4k on a vdev that
is 4k aligned work ok?

Or can the start of a zfs record that''s 16kb for example start at any
sector in the vdev?
-- 
This message posted from opensolaris.org