Bug#708451: kfreebsd-image-9.0-2-amd64: fails to boot from ZFS

[Steven Chamberlain <steven@pyro.eu.org>]

Hi!

On 15/05/13 20:49, christian mock wrote:
> Mounting from zfs:backup-z0/root failed with error 6.

> The issue might be related to the fact that the kernel tells me it's now
> naming the disk devices "ada0" and "ada1" instead of "ad4" and "ad6" [...]

Can I assume these disks are partitioned, probably with an msdos disklabel?

And does the ZFS partition on each disk extend to the end of the drive?


Please try editing the boot commands in GRUB, and add "set
kFreeBSD.vfs.zfs.debug=1";  then you may be able to see exactly what
goes wrong.


> I find the old device paths (e.g. /dev/ad4) in zpool.cache.

What is supposed to happen is, since it can't find /dev/ad4, the kernel
searches all disks and partitions for a ZFS volume matching the expected
UUID.

Unfortunately I think there is a bug in the logic here;  it will look at
/dev/ada0 (whole drive) before it looks at any of the partitions.

I think ZFS labels are stored at the end of the partition, so /dev/ada0
may *look* like the ZFS volume it is searching for.  It attempts to
mount it, but that fails because the start sector is wrong;  then aborts
with error 6.

But really it should have looked at /dev/ada0p4 first (or whatever the
last partition is called).  The end sector is the same, but the start
sector will be somewhere else.

Regards,
-- 
Steven Chamberlain
steven@pyro.eu.org