ZFS i/o error in recent 12.0
Toomas Soome
tsoome at me.com
Tue Mar 20 08:21:02 UTC 2018
> On 20 Mar 2018, at 09:50, Markus Wild <fbsd-lists at dudes.ch> wrote:
>
> Hi there,
>
>> I've been encountered suddenly death in ZFS full volume
>> machine(r330434) about 10 days after installation[1]:
>>
>> ZFS: i/o error - all block copies unavailable
>> ZFS: can't read MOS of pool zroot
>> gptzfsboot: failed to mount default pool zroot
>>
>
>> 268847104 30978715648 4 freebsd-zfs (14T)
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
> I had faced the exact same issue on a HP Microserver G8 with 8TB disks and a 16TB zpool on FreeBSD 11 about a year ago.
> My conclusion was, that over time (and updating the kernel), the blocks for that kernel file were reallocated to a
> later spot on the disks, and that however the loader fetches those blocks, it now failed doing so (perhaps a 2/4TB
> limit/bug with the BIOS of that server? Unfortunately, there was no UEFI support for it, don't know whether that
> changed in the meantime). The pool was always importable fine with the USB stick, the problem was only with the boot
> loader. I worked around the problem stealing space from the swap partitions on two disks to build a "zboot" pool, just
> containing the /boot directory, having the boot loader load the kernel from there, and then still mount the real root
> pool to run the system off using loader-variables in loader.conf of the boot pool. It's a hack, but it's working
> fine since (the server is being used as a backup repository). This is what I have in the "zboot" boot/loader.conf:
>
> # zfs boot kludge due to buggy bios
> vfs.root.mountfrom="zfs:zroot/ROOT/fbsd11"
>
>
> If you're facing the same problem, you might give this a shot? You seem to have plenty of swap to canibalize as well;)
>
please check with lsdev -v from loader OK prompt - do the reported disk/partition sizes make sense. Another thing is, even if you do update the current build, you want to make sure your installed boot blocks are updated as well - otherwise you will have new binary in the /boot directory, but it is not installed on boot block area…
rgds,
toomas
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