How to recover a gmirror from a disaster

[Pawel Jakub Dawidek]

On Tue, Dec 13, 2005 at 08:16:37AM -0500, Mark Bucciarelli wrote:
+> The disaster:
+> 
+>     1. gmirror setup (full disk mirror, da0 + da1)
+> 
+>     2. disk head crash into platter on da1
+> 
+>     3. reboot
+> 
+>     4. mirror starts to sync, hits bad spot on da1, halts
+> 
+>     5. restart (can work for a while b/f bad spot hit)
+> 
+>     6. Enter command "gmirror remove gm0 da1"
+> 
+>     7. Now on restart, da0 will not boot.
+> 
+> On attempting boot on da0, this is the last output b/f system hangs:
+> 
+>     GEOM_MIRROR: Device gm0 created (id=...)
+>     GEOM_MIRROR: Device gm0: provider da0 detected
+>     GEOM_MIRROR: Device gm0 destroyed
+>     GEOM_MIRROR: Device gm0 created (id=...)
+>     GEOM_MIRROR: Device gm0: provider da0c detected
+>     GEOM_MIRROR: Device gm0 destroyed
+>     GEOM_MIRROR: Device gm0 created (id=...)
+>     GEOM_MIRROR: Device gm0: provider da0 detected
+>     GEOM_MIRROR: Device gm0 destroyed
+>     SMP: AP CPU #1 Launched!
+>     Mounting root from ufs:/dev/mirror/gm0s1a
+>     setrootbyname failed
+>     ffs_mountroot: can't find rootvp
+>     Root mount failed: 6

Could you add kern.geom.mirror.debug=3 to your /boot/loader.conf and
boot again?

+> This is 5.4-RELEASE.
+> 
+> The da0 disk is good (I did a surface scan) and I can mount it and 
+> backup the data when I put it in bay #2.
+> 
+> So ...
+> 
+>     Did my command in step #6 cause this mess?   If so, what should I 
+>     have used--forget first?

If da1 was disconnected you should get an error, that mirror is not
complete. Yes, 'forget' is the right command.

+>     How can I get this disk to boot again?

Actually you can simply:

	# gmirror label gm0 da0

No data will be lost. You can also boot from da0 directly.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-geom/attachments/20051214/c7c1186f/attachment.bin