ZFS disk replacement questions

[Steve Polyack]

Derrick Ryalls wrote:
> On Tue, Nov 3, 2009 at 10:21 AM, Steve Polyack <korvus at comcast.net> wrote:
>   
>> Derrick Ryalls wrote:
>>     
>>> 1) In the event of a disk failure, how do I trace back the name such
>>> as adX to a physical drive in the enclosure?  Is there a way to take
>>> the drive offline then use atacontrol to spin it down or something so
>>> it is easy to identify?
>>>
>>>       
>> In my opinion you are best off using glabel(8) to give names to the disks.
>>  This way you can name them in a way that makes sense to you.  Additionally,
>> when you create the ZFS pool you will use the glabel'd names.  This means
>> that the pool will still come up properly if something causes your devices
>> to be numbered differently (i.e. a drive dies and you happen to reboot the
>> system).
>>     
>
> I believe ZFS does this automatically.  Supposedly, if you take a
> working set of RAIDZ drives from one machine and put it in another,
> ZFS will figure out the drives since they get labelled by ZFS
> internally.  My question concerns how to identify the physical disk in
> question based on the adX or glabel name?  Different name in software
> is fine, but if the drive fails I want to make sure I pull the correct
> drive.
>
>   
This is possible, but I don't remember reading that ZFS handles this 
anywhere, and I've seen glabel(8) recommended elsewhere for the same 
reason. 

Either way, you can add your drives one-by-one and label them on the 
enclosure "arraydrive00" and then glabel the individual disks with the 
same name.  This way when ZFS tells you "arraydrive03" is dead/offline, 
you can look at your enclosure and pull the drive with the arraydrive03 
label.
>> Depending on your controller it is also probably worth it to use one of the
>> SATA-specific drivers in FreeBSD 8 - these are ones like ahci(4) and
>> siis(4).  While the generic ata(4) driver will work for pretty much
>> everything, the updated AHCI drivers can take advantage of some more
>> features.  Enable the modules at boot to use them.
>>     
>
> I will look into it, thanks.  The machine in question is 2 year old
> hardware currently with a 3ware raid card.  I will be going software
> raid only, but FreeBSD already recognizes the eSATA drive I have
> attached as a backup device so I know the O/S can at least talk to
> sata drives attached to the mobo.
>
>