Thanks, Dave, you pointed me in the right direction although the FDR documentation makes it sound like it doesn't matter how the DSNENQ option is set. I found this little tidbit in the FDR manual:
If a data set name appears in a DD statement with DISP=SHR within the FDR job (not necessarily in the FDR step, FDR changes the scheduler enqueue for the data set to EXCLUSIVE (DISP=OLD). The data set may be unavailable to other tasks until the FDR job ends. So that answered my question. Rex -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Dave Barry Sent: Tuesday, February 16, 2021 2:44 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: [EXTERNAL] Re: question on enqueues If I'm not mistaken, FDR has an ENQ/NOENQ option. You decide which you can tolerate in your situation. -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Clark Morris Sent: Monday, February 15, 2021 7:24 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: [EXTERNAL] Re: question on enqueues CAUTION! This email originated outside of the organization. Please do not open attachments or click links from an unknown or suspicious origin. ====================================================================== [Default] On 15 Feb 2021 15:37:38 -0800, in bit.listserv.ibm-main rpomm...@sfgmembers.com (Pommier, Rex) wrote: >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: > I suspect the flash process does an exclusive ENQ on all data sets being flashed. Clark Morris >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 lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN 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 lists...@listserv.ua.edu with the message: INFO IBM-MAIN
