dump is stuck

[Poul-Henning Kamp]

In message <20050128144733.GA91982 at green.homeunix.org>, Brian Fundakowski Feldman writes:
>On Fri, Jan 28, 2005 at 09:08:54AM +0200, Danny Braniss wrote:
>> hi,
>> 	while running 'dump 0f - /dist | restore rf -'
>> the dump proc. got stuck, it seems it's waiting on some lock:
>> 
>> UID   PID  PPID CPU PRI NI   VSZ  RSS MWCHAN STAT  TT       TIME COMMAND
>> 
>>  0 30924 30922   0   4  0  3396 2852 sbwait T     p1    1:00.88 dump: 
>> /dev/amrd0s3h: ...
>>  0 30925 30924   1  -8  0  3268 2784 physrd TL    p1    0:53.84 dump 0f - 
>> /dist (dump)
>>  0 30926 30924   1  20  0  3268 2784 pause  T     p1    0:53.69 dump 0f - 
>> /dist (dump)
>>  0 30927 30924   1  20  0  3268 2784 pause  T     p1    0:54.12 dump 0f - 
>> /dist (dump)
>> 
>> (this is  5.3-STABLE, cvs'ed about a week ago, and it's a SMP system).
>> how can i find which lock? or who is holding it?
>
>Is the one in physrd not actually reading anything from the disk right
>now?  I would suspect that should be how you really determine if it's
>hung or not.  You should be able to see how long it's been waiting
>and how long it's due to wait still, using kgdb.

Check also with gstat(8) if there is I/O activity going on and/or if any
I/O requests are stuck.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.