ADSM-L

questions and suggestions

1994-02-17 17:20:17
Subject: questions and suggestions
From: Leonard Boyle <SNOLEN AT VM.SAS DOT COM>
Date: Thu, 17 Feb 1994 17:20:17 EST
I have been  testing adsm for about  two weeks. Like Martha I  am working with
the VM server and I am not a workstation expert. So I have a few questions and
maybe a few requests for changes of the IBM-adsm team. Which brings up another
question. Is  there a group or  person who collect share  requirements for the
adsm product?



VM Server questions:

1) There are no timestamps on the messages in the server console log.
   How many vote for timestamps?

2) There is a "set accounting on" command. I would assume that most
   sites would normally want accounting on or off all the time.
   Should this not be an option in the dsmserv opt file?

3) Should there be an option to write the accounting data to a
   file instead of to cp accounting services. This would be for
   sites that want the data for stats and not for charge back.
   to an VM userid. After all, most of the clients would not have
   an VM userid to have the chages applied against.
   One could see the server saving the data to files stored within it's
   own storage pools. On cms one could use dfsms to recall the data
   when needed.

4) Can IBM-adsm document how the recovery log is used.
   With the doc set that came with PN49454 there are instructions for
   new data-base backup and restore procedures. As part of these
   procedures it calls for:

      4. Issue 3 CKPT commands so that database changes are flushed to
         the database media.

      5. Wait 30-60 seconds before halting the server with the HALT command.

   I would have assumed that shutdown down and restarting the server would
   have cleared the recovery log.

5) I was using tape mount exits to interface the dsmserv mount requests
   with vmtape. This seems to work most of the time, but there are a few
   gray areas with MOUNTWAIT and with a request to have the server
   cancel a mount request.

   On page 334 of the Administrator's Guide release 1 it is written

      "The MOUNTWAIT value is not used by the server to automatically
       cancel requests handled by exit machines. You can use the value in
       the DSMMOUNT EXEC or ignore it, however you see fit."

   On page 333

      "4. If requested, the DSMMOUNT EXEC must cancel the tape mount.
               ...."

   I am not sure how one could do the above when using the vmtape command
   with the vmtape wait option.

   It turns out that what really happens is that at the end of the
   MOUNTWAIT period or when the cancel mount command is used, the
   server issues the cp force command against the mount exit machine.

   The first time I ran into this, the operators were not able to
   find the proper tape within the 60 mins wait period. The server
   issued the force command after waiting 60 mins.
   This did not work since it had only been defined with a cp priv
   class of G. When the operators did finish the mount, vmtape
   attached the volume to dsmserv. dsmserv started using it. But as
   soon as the exit machine started logging off, the dsmserv server
   tried to autolog it and that failed since the exit machine was in
   a logoff/force pending state. The logoff processed finished and
   the server autologed the mount exit machine with a second scratch
   request that was pending after it tried to cancel the first mount.
   Since there was only one mount exit machine defined it could not
   autolog another.

   The good news is that the server knew what to do with both tapes
   even after canceling the request for one of them.
   The bad news, It can try to autolog an exit before cp completes the
   logoff process. I believe that dsmserv needs a short delay between
   seeing a mount exit machine logoff and the next autolog.

   I know that the force/pending problem in CP is not quite what it used
   to be, but I still bad feeling about the production use of force.
   Would it be a viable options to have the dsmserv server autolog
   another mount exit machine that could issue an vmtape cancel command?
   But then maybe the autologing of another mount exit machine could
   cause even more problems. Any good thoughts on this.

   Should the mountwait period be settable by a site? In the config file
   or by command or both?
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