ZFS: i/o error - all block copies unavailable

Mike Tancsa mike at sentex.net
Mon Feb 22 18:31:11 UTC 2016

On 2/22/2016 12:41 PM, Dan Langille wrote:
> I have a FreeBSD 10.2 (with freebsd-update applied) system at home 
> which cannot boot. The message is: ZFS: i/o error - all block
> copies unavailable ZFS: can't read MOS of pool system gptzfsboot:
> failed to mount default pool system
> I booted the box via mfsBSD thumb drive, and was able to import
> the zpool: https://gist.github.com/dlangille/6da065e309301196b9cd 
> <https://gist.github.com/dlangille/6da065e309301196b9cd>
> I have also run: "gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot
> -i 1 XXX" against each drive. I did with the the files provided
> with mfsBSD and with the files from my local 10.2 system.  Neither 
> solution changed the booting problem.

This is a longshot, but I ran into an odd situation like this as well a
few weeks ago.

It seems on the motherboard I was using, when the "DUAL" boot option
is enabled in the BIOS, present all the disks to the loader early in
the boot process.

So, when you escape to the loader prompt, and do

OK lsdev
cd devices:
disk devices:
 disk0:BIOS drive C:
 disk1:BIOS drive D:
 disk2:BIOS drive E:
 disk3:BIOS drive F:
pxe devices:
zfs devices:

In this case, 4 of the disks that are normally part of the zroot were
not there resulting in

ZFS: i/o error - all block copies unavailable

Disabling the "DUAL" option in the BIOS and going back to legacy and
listing all the drives as possible boot drives, then presents to the
zfsloader all the disks, so we see the familiar
BIOS drive C: is disk0
BIOS drive D: is disk1
BIOS drive E: is disk2
BIOS drive F: is disk3
BIOS drive G: is disk4
BIOS drive H: is disk5
BIOS drive I: is disk6
BIOS drive J: is disk7

This is a Supermicro SYS-7048R-C1RT4+ X10DRC-T4+ (BIOS 01/29/2015)

Prior to the reboot, the other drives were not used by the zfs pool, but
were added. Since the old pool didnt need them, it didnt matter.

Its a longshot that this is your problem, but I will takes the chances
today :)


Mike Tancsa, tel +1 519 651 3400
Sentex Communications, mike at sentex.net
Providing Internet services since 1994 www.sentex.net
Cambridge, Ontario Canada   http://www.tancsa.com/

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