>From: Tim Janes <janes@signal.dra.hmg.gb>
>> 
>> Simon Burge <simonb@telstra.com.au> writes:
>> 
>> I saw this at least on three machines, but not so often.  They prints
>> 'syncing disks' and hang.  I'm not yet looking in this problem, but it
>> seems process are waiting struct buf.
>
>We run some 20+ Pentium-Pro's with a common NFS mounted /usr. Since
>upgrading from 1.2.1 to 1.2G this shutdown hang is rock solid on all machines.
>
>I have checked that shutdown works OK if I use /usr on a local disk,
>so seems related to nfs.
>
>I am happy to try some debugging but don't really know how to start.
>
>When in the hung state the machine responds to ping but otherwise appears dead.

I submitted PR kern/4093 about this problem on Sunday.  I wasn't able
to find a fix but I was able to figure out where the hang is
happening.

I *think* there are two distinct problems here, because the NFS /usr
dismount hang seems to happen *before* the "syncing disks" message.

Cheers,
entropy

--
entropy -- it's not just a good idea, it's the second law.