ZFS: how to replace a dead disk?

[James R. Van Artsdalen]

Jeremy Chadwick wrote:
> On Fri, May 28, 2010 at 08:36:38AM -0500, James R. Van Artsdalen wrote:
>> What's the right way to replace a dead disk under ZFS?
>>
>>         replacing   DEGRADED     0     0     0
>>           ada1/old  UNAVAIL      0  256K     0  cannot open
>>           ada1      ONLINE       0     0     0  1.47T resilvered
>> ---
>>
>> It says "replacing" and that the device, vdev and pool are degraded, yet
>> the "resilver" finished hours ago.  I cannot detach the ada1/old entry.
>>
>> Is there some other command I should have used to remove the dead ada1
>> device?
>
> What version of FreeBSD?  Please provide uname -a output and not "8.0"
> or something equally as terse.
>
> Some clarification: you didn't remove the device, you simply told ZFS to
> assuming that the device had been replaced.
>
> What did you do (both physically and software/command-line-wise) *prior*
> to issuing "zpool replace jwrc ada1"?
>
Sorry: my original note contained version information but that isn't in
your reply?

FreeBSD cyclone 9.0-CURRENT FreeBSD 9.0-CURRENT #2 r206111: Fri Apr  2
13:47:20 CDT 2010    
root at cyclone.housenet.jrv:/usr/obj/usr/src/sys/GENERIC  amd64

The original disk is no longer usable by FreeBSD in any way: it returned
a stream of errors & noise on its port in a way that left the system
unable to boot.  I physically replaced that disk with a new disk before
attempting the "zpool replace"

No actions were taken prior to replacing the disk.  I went to the site
to see why the server was unresponsive, saw that one drive was
problematic by watching the activity LEDs, physically replaced that
disk, booted, and logically replaced that disk with "zpool replace jwrc
ada1"