[Info-vax] Need help tracking down a MUTEX state

[Bob Koehler]

In article <a0Wim.359429$jW1.333637 at newsfe22.ams2>, "Ade" <adrian.birkett at blueyonder.co.uk> writes:
> Hi,
> 
> We have a VAX 6000-610 running VMS 6.1. On occasion the system hangs so I've 
> had the operators crash the system as per instructions found elsewhere.
> 
> The dump of the system seems fine except for one process in MUTEX state 
> prio=16, mutex count=0 and PCB$L_EFWM=JIB of this process. On the quota 
> front the only 'anomaly' is that the BUFIO byte count/limit is at 192/65216. 
> None of the other usual suspect quotas are diminished.
> 
> A show proc/chan shows a busy channel to the system disk but no associated 
> file id.

   It is possible to scan through the RMS control blocks and find out what
   file is connected to that channel.  It's been a long time since I've
   done this and I wouldn't try it myself without the listings.

   Having a MUTEX on the JIB could be directly related to the low BUFIO.
   Generally when I see a process low on BUFIO it's doing I/O to a
   mailbox, custom hardware, or network interface that is full or not
   responding.  Generally disks don't do that unless they're dieing.

   The whole thing makes me wonder if you have the audit log on the
   system disk and are running out of space.  VMS' default setup is to
   stop processing until it can get space to continue audits.  You
   can change that via SYSGEN parameters, but you really should migrate
   that critical security data offline on a regular basis.

   And it's not clear, is the whole system hanging or just one critical
   process or one critical job (process tree)?

   SDA will look up the file name for you when used on a live system,
   so you could try running a background job to periodically dump
   that data for the process in question, and look at the last results
   next time you have to force a crash.