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ranjit5311
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Joined: 27 Nov 2005
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 Posted: Wed Apr 26, 2006 8:24 am Post subject: Parallel job updating same VSAM file |
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Hi experts,
My problem is as follow:-
There are 13 jobs which r accessing the same vsam file and udating the same VSAM file. Each job takes about 8-9 mins. So if they are run serially, then total time is more than 2 hrs.
Now, if one run parallelly, then jobs are getting abend with file status - 93.
Is there any technique, by which we can run the job parallelly and reduce the time?
Please let me know u want some more information. |
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kolusu
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Location: San Jose
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| Posted: Wed Apr 26, 2006 8:52 am Post subject: |
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ranjit5311,
1. Dump the vsam CLUSTER to a sequential file
2. Read this file by all jobs and let each job write OUT just the updates into another flat file,so you create 13 flat files from 13 jobs.
3. At the end of the 13th job, concatenate all these 13 output files and sort them on the key sequence and COPY/Repro back to the vsam cluster. Make sure that you define the vsam cluster with REUSE option.
Hope this helps...
Cheers
Kolusu
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Kolusu
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ranjit5311
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Joined: 27 Nov 2005
Posts: 27
Topics: 14
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| Posted: Wed Apr 26, 2006 10:53 am Post subject: |
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Hi friends,
Thanks kolusu for promt reply, can the above objective be achived by ENQ and DEQ logic. Can anyone refer the detail of ENQ/DEQ. How it locks the resourse in context of VSAM file. we r using the following assembler program for ENQ. The share options on the VSAM file are 3-3.
Thanks,
Ranjit |
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kolusu
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Location: San Jose
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| Posted: Wed Apr 26, 2006 11:56 am Post subject: |
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ranjit5311,
I don't think ENQ and DENQ will help in your case. If your running all 13 jobs and updating the same file concurrently , you will get incorrect results. You might miss a couple of updates.
Check this link which discusses about updating a file concurrently
http://mvsforums.com/helpboards/viewtopic.php?t=1202&highlight=enq
Hope this helps...
Cheers
Kolusu
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Kolusu
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ranjit5311
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Joined: 27 Nov 2005
Posts: 27
Topics: 14
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| Posted: Wed Apr 26, 2006 1:45 pm Post subject: |
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Kolusu,
I have gone through the link that u have given. It is discuss mainly on the sequential file. But here its a VSAM file. Does the shr option make a difference.
Also the last post say :-
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Not strictly true. Load libraries are normally updated with DISP=SHR so that other jobs can continue to execute programs from them. The linkage editor/binder uses a special ENQ/RESERVE to insure that only one program can be updated at a time. If you force them to use DISP=OLD when updating, then the load library could only be updated when noone was using it. Linklist libraries, which are normally ENQed by LLA, could never be updated.
but for datasets without this special protection, you are right.
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Here with Enq and Denq, we can update the file with disp = shr . we will use ENQ before the rewrite and Denq after rewirite.
Is this possible. If yes what should the parameter in ENQ.
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