IEBGENER may do an ENQ of its own, and OPEN does a different ENQ, but the Initiator only does a shared ENQ for that SYSUT2 with DISP=SHR.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Discussion List [[email protected]] on behalf of Radoslaw Skorupka [[email protected]] Sent: Tuesday, February 16, 2021 9:37 AM To: [email protected] Subject: Re: question on enqueues 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 > > The information contained in this message is confidential, protected from > disclosure and may be legally privileged. If the reader of this message is > not the intended recipient or an employee or agent responsible for delivering > this message to the intended recipient, you are hereby notified that any > disclosure, distribution, copying, or any action taken or action omitted in > reliance on it, is strictly prohibited and may be unlawful. If you have > received this communication in error, please notify us immediately by > replying to this message and destroy the material in its entirety, whether in > electronic or hard copy format. Thank you. > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
