Date: Mon, 2 Apr 2012 16:00:14 GMT From: George Hartzell <hartzell@alerce.com> To: freebsd-fs@FreeBSD.org Subject: Re: kern/166566: [zfs] zfs split renders 2 disk (MBR based) mirror unbootable Message-ID: <201204021600.q32G0Eb1019682@freefall.freebsd.org>
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The following reply was made to PR kern/166566; it has been noted by GNATS.
From: George Hartzell <hartzell@alerce.com>
To: Andriy Gapon <avg@FreeBSD.org>
Cc: bug-followup@FreeBSD.org,
hartzell@alerce.com
Subject: Re: kern/166566: [zfs] zfs split renders 2 disk (MBR based) mirror
unbootable
Date: Mon, 2 Apr 2012 08:47:53 -0700
Thanks for following up on this.
Andriy Gapon writes:
>
> A few things missing from your port:
>
> 1. "Doesn't boot" is quite a poor description in comparison with
> other details that you provided. You should give more detailed
> information of the boot failure.
As the kernel is loading it fails to mount the root partition and
presents one with the minimal mountroot dialog. Attempting to boot
from zfs:zroot or zfs:zsplitroot fails. I remember that a question
mark lists various other devices but don't remember the particulars.
> 2. gpart information for ada3
Identical to ada1. Both disks have an MBR with one slice, which has a
BSD label with two partitions, a (926GB, type freebsd-zfs) and b
(5.5GB, type freebsd-swap).
(delicious)[8:45am]~>>gpart show ada1
=> 63 1953525105 ada1 MBR (931G)
63 1953525105 1 freebsd [active] (931G)
(delicious)[8:45am]~>>gpart show ada1s1
=> 0 1953525105 ada1s1 BSD (931G)
0 1941962752 1 freebsd-zfs (926G)
1941962752 11562353 2 freebsd-swap (5.5G)
(delicious)[8:46am]~>>gpart show ada3
=> 63 1953525105 ada3 MBR (931G)
63 1953525105 1 freebsd [active] (931G)
(delicious)[8:46am]~>>gpart show ada3s1
=> 0 1953525105 ada3s1 BSD (931G)
0 1941962752 1 freebsd-zfs (926G)
1941962752 11562353 2 freebsd-swap (5.5G)
Both have boot bits set up like this:
gpart bootcode -b /boot/boot0 adaX
dd if=/boot/zfsboot of=/dev/adaXs1 count=1
dd if=/boot/zfsboot of=/dev/adaXs1a skip=1 seek=1024
> 3. You don't say which disk ended up as zroot and as zsplitroot
> after the split.
zpool status showed only
zroot ada3s1a
and zpool import showed
zsplitroot ada1s1a
> 4. You don't say which disk is configured as a boot disk in BIOS.
This is a mac pro (tower), so BIOS is kind of a slippery concept. I
leave the 'startup disk' set to the (other) OS X disks. On power up I
hold down the option key and am presented with a dialog from which I
can select any of the bootable devices in the box.
When things are working correctly I can boot from either of the disks
in the ZFS mirror and things go well. Now that I've upgraded I can
even pull one of the disks before powering up and boot from the other
(older zfs bootstrapping stuff used to have a problem with broken
mirrors).
After the zfs split I am unable to boot from either disk.
g.
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