7.2-RELEASE-p4, IO errors & RAID1 failure

[Matthew Lear]

On Tue, 2010-06-22 at 20:04 +0100, Bob Bishop wrote:
> Hi,
> 
> On 22 Jun 2010, at 08:45, Jeremy Chadwick wrote:
> 
> > On Mon, Jun 21, 2010 at 10:33:12PM +0100, Matthew Lear wrote:
> >> [tale of woe elided]
> > 
> > I don't really have any other thoughts on the matter, sadly.
> > [helpful suggestions elided]
> > 
> > Anyone else have ideas/recommendations?
> 
> The disks sure look OK. I wouldn't rule out the controller(s), I've had various chipsets fail in odd ways.
> 

Thanks Bob. I think we all thought the same.
I've actually just rebooted the machine and FreeBSD no longer boots.
This isn't what I was expecting at all. Something has clearly gone wrong
with some file system metadata.

When I commissioned the machine I installed an 'early' bootloader
(apologies for perhaps using an incorrect term) which boots FreeBSD by
default (F1 option) or from Drive 1 (F5). Drive 1 is the DVD drive.

It appears to be the case that the early bootloader tries to boot
FreeBSD and fails. I get the messages:

error 1 lba 795079
Invalid format

FreeBSD/i386 boot
Default: 0:ad(0,a)/boot/kernel/kernel
boot:
error 1 lba 786815
No /boot/kernel/kernel

FreeBSD/i386 boot
Default: 0:ad(0,a)/boot/kernel/kernel
boot:

...and I'm at a boot prompt.

So, given that ad0 was the failed disk, the bootloader has failed to
find specific boot data on ad0 and dropped me into a boot prompt.

I'm tempted to replace the boot line with 0:ad(2,a)/boot/kernel/kernel
or should that be 2:ad(0,a)/boot/kernel/kernel but I'm a little
suspicious of doing anything at this point?

Can anybody offer any guidance of what I can do to restore my system? I
was able to shut down the machine cleanly (shutdown -p now) and despite
the RAID mirror going offline, everything seemed to be behaving normally
(expected I guess given that I just lost some redundancy).

I'm just that little bit more worried now :-( If the disks are ok, what
on earth could have happened and more importantly, how can I restore
what was an operational system when I shut it down?!

Puzzled....
--  Matt