ffs snapshot lockup

[Vivek Khera]

On Sep 22, 2006, at 3:03 PM, Kris Kennaway wrote:

>> I know this is very un-useful as a bug report, but I'm putting this
>> out in case anyone else has noticed this.  It has never happened to
>> us before when we were running 5.4 and then 6.1 on this box.  Nothing
>> else changed on the system during this time.
>
> Yep, we'd need additional debugging to proceed.

How does one debug a system where the disk sub-system is frozen?  I  
have serial console with DDB/KDB built into the kernel and debugging  
symbols too.  Is that the only option here?

We're gonna try the full level 0 backup again monday and if it locks  
up I'll try to figure it out, but could use some hints as to where to  
poke in the kernel.