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Freeware procedure SHADOW_TRACK.COM goes whacko

 
Neil Ashworth_1
Occasional Advisor

Freeware procedure SHADOW_TRACK.COM goes whacko

For the past 5 years or more, I have been using the freeware procedure SHADOW_TRACK.COM to watch the shadow sets on multiple OpenVMS 7.3-2 systems. Basically its a batch job that every 5 minutes will scan the mounted shadow sets, and if any members have been added or removed since the last run, it will send a notification email. Nary a problem, nary a hiccup, runs rock solid ... until now.

Now, on one particular system, when it "wakes" the job will jump to priority 16, take over the system and put all other processes in COM state. The system stays locked up for about 15-20 seconds until SHADOW_TRACK completes the scan and goes to sleep for 5 minutes. When it wakes, the pattern is reproduced.

I have tried turning verify on, and using the SET PREFIX command to time stamp each DCL line, but it did not help. As far as the batch jop is concerned, it woke up, ran the scan and went back to sleep, all within 1 second.

I have looked at the precedure, but really it does nothing more than a bunch of F$GETDVI statements, and a ton of symbol comparisons.

If someone could take 5 minutes and look at the code, perhaps fresh eyes will see something I missed.

Thanks, Neil
5 REPLIES 5
Hoff
Honored Contributor

Re: Freeware procedure SHADOW_TRACK.COM goes whacko

The symptoms you describe could be consistent with a process holding a mutex lock. Confirm your patches are current for OpenVMS, DCL, I/O, drivers and particularly shadowing; there are various critical patches in these areas.
Wim Van den Wyngaert
Honored Contributor

Re: Freeware procedure SHADOW_TRACK.COM goes whacko

In the future please post your enclosure as .txt. Many (big) companies block .com.

Wim
Wim
Dennis Handly
Acclaimed Contributor

Re: Freeware procedure SHADOW_TRACK.COM goes whacko

>Wim: In the future please post your enclosure as .txt.

You can use this for .txt:
http://forums.itrc.hp.com/service/forums/getattachment.do?attachmentId=330398&ext=.txt
Jur van der Burg
Respected Contributor

Re: Freeware procedure SHADOW_TRACK.COM goes whacko

As Hoff said, make sure the system is up to rev. The procedure only does getdvi's which should be harmless. The symptoms appear to be that something's hosed on the system, if possible you should crash the system when it's in this state and save the dumpfile. Analyzing the dump may give a clue. This has nothing to do with the command procedure itself.

Jur.
John Gillings
Honored Contributor

Re: Freeware procedure SHADOW_TRACK.COM goes whacko

Neil,
What does "@SYS$SUPPORT:SHADOW_CONFIG GLOBAL_SYMBOLS" do?

It may also be instructive to insert a SHOW SYMBOL/ALL and SHOW SYMBOL/GLOBAL/ALL immediately after that call to see what devices it found.
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