Re: wedged machine in disklabel run from /etc/daily

[Brook Milligan <brook%nmsu.edu@localhost>]

> On May 13, 2019, at 3:43 AM, Michael van Elst <mlelstv%serpens.de@localhost> wrote:
> 
> brook%nmsu.edu@localhost (Brook Milligan) writes:
> 
>> # ps -lp 4904
>> UID  PID PPID  CPU PRI NI  VSZ  RSS WCHAN  STAT TTY    TIME COMMAND
>> 0 4904    1 1968 127  0 9924 1160 tstile D    ?   0:00.00 disklabel sd0 
> 
>> What exactly does the 'tstile' mean?
> 
> It means, that the process is waiting for a mutex. There is no information on
> what mutex it is waiting on, probably something related to a disk driver.
> 
> You can use the 'crash' utility or the DDB kernel debugger to get a
> backtrace. This shows where the process is waiting, which is a good
> hint on what it is waiting for.

What is your suggestion for how to use 'crash'?  I have never done that so I am not sure what commands are available once I run it.  Running ps in crash does not seem to reveal much, but I'm not really sure how to interpret all the hex information.

I am hesitant to drop into a kernel debugger, because the machine is 8000 miles away from me.

>> What can be done (short of a power reset) to unwedge this machine?
> 
> Probably nothing.

This sounds like the only option is to get someone to power cycle it.  Is that correct?  It would still be nice to know what happened so I can understand what to do in the future; hence my questions about troubleshooting.

Thanks for your help.

Cheers,
Brook