ZFS: Can't repair raidz2 (Cannot replace a replacing device)

Rich rincebrain at gmail.com
Thu Dec 24 00:32:55 UTC 2009

That's fascinating - I'd swear it used to be the case (in
Solaris-land, at least) that resilvering with a smaller vdev resulted
in it shrinking the available space on other vdevs as though they were
all as large as the smallest vdev available.

In particular, I'd swear I've done this with some disk arrays I have
laying around with 7x removable SCA drives, which I have in 2, 4.5, 9,
and 18 GB varieties...

But maybe I'm just hallucinating, or this went away a long time ago.
(This was circa b70 in Solaris.)

I know you can't do this in FreeBSD; I've also run into the
"insufficient space" problem when trying to replace with a smaller

- Rich

On Wed, Dec 23, 2009 at 7:29 PM, Steven Schlansker
<stevenschlansker at gmail.com> wrote:
> On Dec 22, 2009, at 3:15 PM, Miroslav Lachman wrote:
>> Steven Schlansker wrote:
>>> As a corollary, you may notice some funky concat business going on.
>>> This is because I have drives which are very slightly different in size (<  1MB)
>>> and whenever one of them goes down and I bring the pool up, it helpfully (?)
>>> expands the pool by a whole megabyte then won't let the drive back in.
>>> This is extremely frustrating... is there any way to fix that?  I'm
>>> eventually going to keep expanding each of my drives one megabyte at a time
>>> using gconcat and space on another drive!  Very frustrating...
>> You can avoid it by partitioning the drives to the well known 'minimal' size (size of smallest disk) and use the partition instead of raw disk.
>> For example ad12s1 instead of ad12 (if you creat slices by fdisk)
>> of ad12p1 (if you creat partitions by gpart)
> Yes, this makes sense.  Unfortunately, I didn't do this when I first made the array
> as the documentation says you should use whole disks so that it can enable the write
> cache, which I took to mean you shouldn't use a partition table.  And now there's no
> way to fix it after the fact, as you can't shrink a zpool even by a single
> MB :(
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