Few remarks:
1. DISP=SHR does not guarantee the SHR in effect. Actual ENQ can be
different. Test: SYSUT2 in IEBGENER step and DISP=SHR - you will see
exclusive ENQ.
2. I don't know FDRflash, but tools using DASD Point in Time replication
features (Flashcopy, Snapshot, TimeFinder...) can work with no regular
ENQ processing.
--
Radoslaw Skorupka
(looking for new job)
Lodz, Poland
W dniu 16.02.2021 o 00:37, Pommier, Rex pisze:
I have one that's puzzling me and I'm sure there's a simple solution/answer.
I'm seeing 2 jobs running on a single system that are hitting an enqueue
problem on a parmlib. The JCL in both jobs has DISP=SHR, yet one of the jobs
has an exclusive ENQ on the library. Here's the scenario:
Job A is a system backup job. It does a bit of early processing, then runs an
FDRFlash of most of our disk, then runs FDR to back up the offline volumes
created in the flash as well as some volumes that weren't flashed. Once the
backup step is done (3 hours later) it does some more post backup processing.
There are 3 steps in the post processing that allocate this parmlib, all
allocating the same member - call it A.B.C.PARM(MEMB), all with DISP=SHR.
Job B is a cyclical job that runs in a matter of a few seconds and runs every 5
minutes. It also has A.B.C.PARM(MEMB) DISP=SHR as well as A.B.C.PARM(MEMZ)
DISP=SHR in a different step.
Timing:
Job A started and was doing its preliminary work.
Job B started and ended successfully.
Job A does the flash step and starts the full volume dumps.
Job B comes along again and can't start because job A has an exclusive ENQ on
A.B.C.PARM. Job B does not start until job A has completed the last step with
A.B.C.PARM in the JCL.
A couple other points are that A.B.C.PARM is on a volume that was flashed, so
the source volume wasn't part of the backup. The job steps in both jobs with
A.B.C.PARM in them are all conditional steps that actually didn't execute.
So my question is what could have caused an ENQ change from SHR to OLD when the
JCL explicitly has SHR?
TIA,
Rex
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