zfs discuss - Sep 2012 - finding smallest drive that can be used to replace

"What is the smallest sized drive I may use to replace this dead
drive?"

That information has to be someplace because ZFS will say that drive Q is too
small.  Is there an easy way to query that information?

On 09/05/2012 05:06 AM, Yaverot wrote:
> "What is the smallest sized drive I may use to replace this dead
drive?"
> 
> That information has to be someplace because ZFS will say that drive Q is
too small.  Is there an easy way to query that information?
I use fdisk to find this out. For instance say your drive you want to
find the size of is c2t4d0, then do:

# fdisk /dev/rdsk/c2t4d0p0

Near the top fdisk will print this kind of drive info:

             Total disk size is 9345 cylinders
             Cylinder size is 12544 (512 byte) blocks

Simply multiply the numbers and you get the result:

# echo ''9345 * 12544 * 512'' | bc
60018524160

And that''s the size of the drive in 8-bit bytes.

Cheers,
--
Saso

--- skiselkov.ml at gmail.com wrote:
>On 09/05/2012 05:06 AM, Yaverot wrote:
> "What is the smallest sized drive I may use to replace this dead
drive?"
> 
> That information has to be someplace because ZFS will say that drive Q is
too small.  Is there an easy way to query that information?
>I use fdisk to find this out. For instance say your drive you want to find
the size of is c2t4d0, then do:
># fdisk /dev/rdsk/c2t4d0p0
I guess that''ll teach me yet again to ask the right question.

Scenario:
machine has multiple pools (rpool, tank)
pool tank has multiple vdevs all raidz2, the drives in the pool vary from 500G
to 3T in capacity.
c64t0d0 has failed and no longer responds to I/O, so it can''t be
queried with the fdisk trick above.
I know the failed disk is 1.5T, but before I go buy the replacement, I want to
know if I can replace it with a 1T, or if it needs to be 2T (since 1.5T was a
stopgap size instead of a longterm not-too-big-not-too-small size I saw it).
ZFS knows that a device I''m about to stick in is too small, so how do I
query that information for required minimum size?

Query the size of the other drives in the vdev, obviously. ;) So long as
the replacement is larger than the smallest remaining drive, it''ll
work.
On Sep 5, 2012 8:57 AM, "Yaverot" <Yaverot at computermail.net>
wrote:
>
>
> --- skiselkov.ml at gmail.com wrote:
> >On 09/05/2012 05:06 AM, Yaverot wrote:
> > "What is the smallest sized drive I may use to replace this dead
drive?"
> >
> > That information has to be someplace because ZFS will say that drive Q
> is too small.  Is there an easy way to query that information?
>
> >I use fdisk to find this out. For instance say your drive you want to
> find the size of is c2t4d0, then do:
>
> ># fdisk /dev/rdsk/c2t4d0p0
>
> I guess that''ll teach me yet again to ask the right question.
>
> Scenario:
> machine has multiple pools (rpool, tank)
> pool tank has multiple vdevs all raidz2, the drives in the pool vary from
> 500G to 3T in capacity.
> c64t0d0 has failed and no longer responds to I/O, so it can''t be
queried
> with the fdisk trick above.
> I know the failed disk is 1.5T, but before I go buy the replacement, I
> want to know if I can replace it with a 1T, or if it needs to be 2T (since
> 1.5T was a stopgap size instead of a longterm not-too-big-not-too-small
> size I saw it).
> ZFS knows that a device I''m about to stick in is too small, so how
do I
> query that information for required minimum size?
>
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>
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