zfs discuss - Mar 2007 - renumbering and its potential side effects.

i am forced to reinstall s10u3 on my x4500. SP 1.1.1. exported zpool,
and discovered during the reinstall that the controller numbers have 
changed. what used to be c5t0d0 is now c6t0d0. it it happens the exported
zpool is using only half the disks, and has no reference to a c6t0d0, but
still a disconcerting situation as i have no idea what the effects of
this controller renumbering may be. i may have had a pool that had
5x9+1 layout, that would have used c6t0d0 and c6t4d0...

puzzled  and concerned...

oz
-- 
ozan s. yigit | oz at somanetworks.com | o: 416-348-1540
if you want to have your head in the clouds
you need to keep your feet on the ground. -- terry pratchett

zfs-discuss-bounces at opensolaris.org wrote on 03/01/2007 10:05:44 AM:
> i am forced to reinstall s10u3 on my x4500. SP 1.1.1. exported zpool,
> and discovered during the reinstall that the controller numbers have
> changed. what used to be c5t0d0 is now c6t0d0. it it happens the exported
> zpool is using only half the disks, and has no reference to a c6t0d0, but
> still a disconcerting situation as i have no idea what the effects of
> this controller renumbering may be. i may have had a pool that had
> 5x9+1 layout, that would have used c6t0d0 and c6t4d0...
>
I have not tested much about it, but I believe the code around
export/import handles device name changes fine.  I seem to remember that it
scans each available disk for zfs sigs and is able to import just fine.

> puzzled  and concerned...
about the device rename?  I guess I am puzzled as well,  what did you
upgrade from S10u2 (self install or factory install)?

-Wade

On Thu, Mar 01, 2007 at 11:05:44AM -0500, ozan s. yigit
wrote:
> i am forced to reinstall s10u3 on my x4500. SP 1.1.1. exported zpool,
> and discovered during the reinstall that the controller numbers have 
> changed. what used to be c5t0d0 is now c6t0d0. it it happens the exported
> zpool is using only half the disks, and has no reference to a c6t0d0, but
> still a disconcerting situation as i have no idea what the effects of
> this controller renumbering may be. i may have had a pool that had
> 5x9+1 layout, that would have used c6t0d0 and c6t4d0...
Exporting the pool was the correct thing to do.  The import should
succeed even though the device names have all changed completely (you
can test this with USB sticks if you want).

Nico
--

It should not matter if the controller numbers have changed.  There are
a few scenarios:

1. If the pool is active, and the underlying driver supports devids,
   then ZFS will still be able to open the correct devices.  If the
   underlying driver doesn''t support devids, or if the devids have
   also changed (both extremely unlikely), then the pool will come
   up faulted.

2. If the pool is exported, then ''zpool import'' is able to
recover
   arbitrary reconfigurations - devids/paths/whatever.  It
   reconstructs the configuration based solely on the on-disk data
   it discovers while walking disks in the system.

Hope that helps,

- Eric

On Thu, Mar 01, 2007 at 11:05:44AM -0500, ozan s. yigit
wrote:
> i am forced to reinstall s10u3 on my x4500. SP 1.1.1. exported zpool,
> and discovered during the reinstall that the controller numbers have 
> changed. what used to be c5t0d0 is now c6t0d0. it it happens the exported
> zpool is using only half the disks, and has no reference to a c6t0d0, but
> still a disconcerting situation as i have no idea what the effects of
> this controller renumbering may be. i may have had a pool that had
> 5x9+1 layout, that would have used c6t0d0 and c6t4d0...
> 
> puzzled  and concerned...
> 
> oz
> -- 
> ozan s. yigit | oz at somanetworks.com | o: 416-348-1540
> if you want to have your head in the clouds
> you need to keep your feet on the ground. -- terry pratchett
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock