On 24 November 2010 01:40, David Magda <dma...@ee.ryerson.ca> wrote:
> It's a per-pool property, and currently hard coded to a value of nine
> (i.e., 2^9 = 512).
On 27 November 2010 14:11, Brandon High <bh...@freaks.com> wrote:
> The ashift is set in the pool when it's created and will persist
> through the life of that pool. If you set it at pool creation, it will
> stay regardless of OS upgrades.
>
I beg to differ:
$ zdb -C | grep -B1 -a9 "type: 'raidz'"
children[0]:
type: 'raidz'
id: 0
guid: 2697156371937180589
nparity: 1
metaslab_array: 30
metaslab_shift: 37
ashift: 12
asize: 18003469271040
is_log: 0
create_txg: 4
--
children[1]:
type: 'raidz'
id: 1
guid: 8374290131789411367
nparity: 1
metaslab_array: 28
metaslab_shift: 37
ashift: 12
asize: 18003469271040
is_log: 0
create_txg: 4
--
children[2]:
type: 'raidz'
id: 2
guid: 7520329545218679233
nparity: 1
metaslab_array: 64
metaslab_shift: 37
ashift: 9
asize: 17998477000704
is_log: 0
create_txg: 42736
For the pool:
$ zpool status tank | grep -v d0
pool: tank
state: ONLINE
scan: resilvered 0 in 0h0m with 0 errors on Thu Nov 25 22:01:52 2010
config:
NAME STATE READ WRITE CKSUM
tank ONLINE 0 0 0
raidz1-0 ONLINE 0 0 0
raidz1-1 ONLINE 0 0 0
raidz1-2 ONLINE 0 0 0
I created the pool with the modified binary from
http://digitaldj.net/2010/11/03/zfs-zpool-v28-openindiana-b147-4k-drives-and-you/,
with
just the top two vdevs (Samsung HD204UI's + Seagate LP's; with 512B emulated
from 4KiB physical sector drives). It was later expanded using the default
(normally installed in SX11) zpool binary, with the third vdev of Hitachi
7200rpm drives (512B native drives).
I'm presently trying to confirm this with something like iosnoop, and
struggling to isolate which vdev is which. I can confirm that there are 512B
reads/writes by zpool-tank (iotop). I'd presume that it's limited to the
third (bottom) vdev.
Newsflash for the internet: you can have pools with mixed ashifts. This
means that you don't need to rebuild your pool from scratch to integrate
4KiB physical sector drives. Please, Oracle, allow users to provide ashift
during zpool create and zpool add. Please!
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