ZFS: drive replacement performance

[Brooks Davis]

On Tue, Jul 07, 2009 at 12:56:14PM -0700, Mahlon E. Smith wrote:
> 
> I've got a 9 sata drive raidz1 array, started at version 6, upgraded to
> version 13.  I had an apparent drive failure, and then at some point, a
> kernel panic (unrelated to ZFS.)  The reboot caused the device numbers
> to shuffle, so I did an 'export/import' to re-read the metadata and get
> the array back up.
> 
> Once I swapped drives, I issued a 'zpool replace'.
> 
> That was 4 days ago now.  The progress in a 'zpool status' looks like
> this, as of right now:
> 
>  scrub: resilver in progress for 0h0m, 0.00% done, 2251h0m to go
> 
> ... which is a little concerning, since a) it appears to have not moved
> since I started it, and b) I'm in a DEGRADED state until it finishes...
> if it finishes.
> 
> So, I reach out to the list!
> 
>  - Is the resilver progress notification in a known weird state under
>    FreeBSD?
> 
>  - Anything I can do to kick this in the pants?  Tuning params?
> 
>  - This was my first drive failure under ZFS -- anything I should have
>    done differently?  Such as NOT doing the export/import? (Not sure
>    what else I could have done there.)

I'm seeing essentially the same think on an 8.0-BETA1 box with an 8-disk
raidz1 pool.  Every once in a while the system makes it to 0.05% done
and gives a vaguely reasonable rebuild time, but it quickly drops back
to reports 0.00% and it's basically not making any forward progress.  In
my case this is a copy of a mirror so while it would be a bit annoying
to rebuild, the system could be rebuilt fairly easily.

On thing I did just notice is that my zpool version is 13, but my file
systems are all v1 rather than the latest (v3).  I don't know if this is
relevant or not.

-- Brooks
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