Can't use gpt labels re-importing pool

[Jeremy Chadwick]

On Thu, Nov 26, 2009 at 02:40:17AM -0600, Scot Hetzel wrote:
> On 11/26/09, Arnaud Houdelette <arnaud.houdelette at tzim.net> wrote:
> > I just upgraded from 7.2 to 8.0.
> >  Under 7.2 the pool was like :
> >        NAME           STATE     READ WRITE CKSUM
> >        tank           ONLINE       0     0     0
> >          raidz1       ONLINE       0     0     0
> >            ad6p1     ONLINE       0     0     0
> >            ad10p1     ONLINE       0     0     0
> >            ad8p1     ONLINE       0     0     0
> >            ad4p1  ONLINE       0     0     0
> >
> >  I'd like to use gpt labels or gptids reimporting the pool.
> >  # ls /dev/gpt
> >  disk1 disk2 disk3 disk4
> >  # ls /dev/gptid
> >  0902db4e-d462-11de-96bd-001d923bc7a0
> > 9fb111f8-d426-11de-99bc-001d923bc7a0
> >  1be29091-d9dc-11de-9f4a-001d923bc7a0
> > ffb4e96a-d497-11de-96bd-001d923bc7a0
> >
> >  I did # zpool import -d /dev/gpt tank
> >  and I got
> >        tank           ONLINE
> >          raidz1       ONLINE
> >            ada1p1     ONLINE
> >            ada3p1     ONLINE
> >            ada2p1     ONLINE
> >            gpt/disk4  ONLINE
> >
> >  Now, how to force zpool import to only use gpt labels (or uuids) ? Or at
> > least get back to coherent situation ( zpool export tank /  zpool import
> > gives the same now. and zpool import -d /dev, as zpool import -d /dev/gptid
> > gives nothing ) ?
> >
> 
> Use 'zpool replace' to change the zfs pool to use the gpt names:
> 
> zpool replace tank ada1p1 gpt/disk1
> zpool replace tank ada2p1 gpt/disk2
> zpool replace tank ada3p1 gpt/disk3
> 
> NOTE: make sure you use the correct gpt names for each partition, as
> the above assumes that ada1p1 is labeled as disk1.

I'm a bit curious about something, so maybe someone can help me
understand:

Why are people bothering with GPT labels (or in some cases, glabels)
when AHCI (whether it be ataahci.ko or ahci.ko) is in use?  Under what
circumstance would the device name change dynamically in this situation?

I've never witnessed this happening with AHCI, at least on Intel
systems, and I've hot-swapped hard disks many times over.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |