Pack of CAM improvements

[Freddie Cash]

On Fri, Jan 22, 2010 at 10:28 AM, Steve Polyack <korvus at comcast.net> wrote:

> On 01/22/10 11:48, Freddie Cash wrote:
>
>> In my testing of pulling drives at random (using a 3Ware 9550SXU or 9650SE
>>>
>>>
>> controller), you have to "zpool offline<pool>  <device>" while the drive
>> is
>> unplugged, before you can re-insert the same disk or a different disk.
>>  Without doing that step, it's very hard to re-insert the same disk, or
>> replace it with a new one, without rebooting.
>>
>> Took me a couple of reboots and drive replacements before I figured that
>> one
>> out.  :)
>>
>>
> I think you can do it without the 'zpool offline <pool> <device>' command;
>  I may be wrong, but I believe you can use 'zpool replace' to accomplish
> what you're trying to do.  i.e. if you have a bad drive ada3, and take it
> out, then replace it with a new disk, you can issue a 'zpool replace <pool>
> /dev/ada3 /dev/ada3' (yes, the same device is specified twice). ZFS should
> recognize that its a different disk and/or that it is lacking ZFS metadata
> and begin to resilver the pool onto the new device.  If you watch 'zfs
> status' in the process you'll see something like:
>
> Yes, that does work ... but it's not nearly as reliable as doing the
offline first.

If you do things in the right order, drives can be replaced and resilvering
started within minutes (our process takes a little less than 5 minutes, but
the bulk of that is removing the dead drive from the caddy, and adding the
new drive to the caddy).

Do things in the wrong order, and it can take 15 minutes or more, and may
require rebooting the system (as our manager discovered trying to replace a
drive while I was away).  :)

Just because there are shortcuts available ... doesn't mean you should
always take them.  :D

-- 
Freddie Cash
fjwcash at gmail.com