ZFS: i/o error - all block copies unavailable on large disk number machines

[Steven Hartland]

----- Original Message ----- 
From: "Chuck Swiger"

> On Jan 23, 2012, at 9:04 AM, Steven Hartland wrote:
>> After some digging we discovered that this was likely due
>> to the fact that the BIOS only enumerates the first 12 disks
>> and this machine has more than that in the root zpool which
>> was a striped raidz2 volume. This in turn means that the
>> bootcode can't complete and hence the machine can't boot.
> 
> As far as I can tell, ZFS best practices guides recommend no
> more than nine drives in a group/pool.  Putting more than that
> into a pool, much less something you are trying to boot from,
> seems like a fine experiment to make but is not something which
> I would rely upon...

Not something I've seem made clear, but quite possibly. Even with
9 disks you could easily get this if the BIOS doesn't see all of
said disks, be that initially or due to disks added to the machine.

For reference the original install was done on a zpool with 6 disks
in a raidz2 config but then 6 additional disks where added to expand
capacity.

It was only when the new kernel was installed that data required
to boot was then written to disks in the seconds raidz2 which is
inaccessible to the boot code even though in perfect working order
on a booted system.

So something to document, watch out for and potentially safe
guard against?

It maybe something specific to machines with legacy BIOS hence not
an issue with Sun kit?

What made it more interesting is the boot code could see the
directory structure but clearly not all of the required data.

Would it be possible for the boot code to provide a more coherent
message in this case?

    Regards
    Steve

================================================
This e.mail is private and confidential between Multiplay (UK) Ltd. and the person or entity to whom it is addressed. In the event of misdirection, the recipient is prohibited from using, copying, printing or otherwise disseminating it or any information contained in it. 

In the event of misdirection, illegible or incomplete transmission please telephone +44 845 868 1337
or return the E.mail to postmaster at multiplay.co.uk.