Billy, To answer one of your questions specifically -
While we have been talking here, I have looked, and found some jobs with //SORTWK01 DD UNIT=(WORK,5)... and this will not work, is that right, Sri Kolusu? I would only get the first volume anyway? You are correct, this will only use the first volume. Nothing will get allocated on subsequent volumes. Rex -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Billy Ashton Sent: Monday, July 3, 2023 1:14 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: [EXTERNAL] Re: SORTWK space usage Thanks everyone - these are good recommendations. However, the guy who came to me first has a job that sorts 450 million records of 110 bytes, and I can't see how I could run SORT without specifying SORTWK DD statements. Are there special configuration options I can verify that we have in place to help my comfort level that I could eliminate SORTWK DD? If the programming team are not convinced, does this look right, based on the discussion - and based on a 100% Disk sort, which is not likely? 450mill * 110 * 1.5 = 74250000000 = 69GB so maybe SORTWK01 - SORTWK10 //SORTWK01 DD UNIT=WORK,DSNTYPE=LARGE,SPACE=(CYL,(4000,1000)) to //SORTWK10 DD UNIT=WORK,DSNTYPE=LARGE,SPACE=(CYL,(4000,1000)) and this will give me 4000 + (15*1000) on each, or 40000c primary + (up to 150 * 1000) secondary While we have been talking here, I have looked, and found some jobs with //SORTWK01 DD UNIT=(WORK,5)... and this will not work, is that right, Sri Kolusu? I would only get the first volume anyway? Thank you and best regards, Billy Ashton ------ Original Message ------ From "Farley, Peter" <0000031df298a9da-dmarc-requ...@listserv.ua.edu> To IBM-MAIN@listserv.ua.edu Date 7/3/2023 12:44:43 PM Subject Re: SORTWK space usage >I will add on to Sri's excellent answer with my very STRONG recommendation NOT >to use hard-coded SORTWK's in your JCL. Both of the major SORT vendors (IBM >and Syncsort) do a far, far better job of estimating necessary SORTWK space >and memory utilization than any human could hope to do. > >I also STRONGLY recommend that you give your JCL and program-controlled SORT >steps as much memory in the REGION parameter as your installation allows for >production and test jobs. Both of the major SORT programs will figure out how >much of that memory to use, whether and how much of it to use in the current >WLM environment, and will make VERY effective use of as much of it as they can >to cut down on SORT execution and elapsed time. Memory is (relatively) cheap, >don't be afraid to use all you've got available to shorten your SORT times. > >My basic advice is don't try to second-guess these very intelligent programs - >they each have more than half a century of practice and experience that none >of us can match, even those of us who have been around that long. > >Peter > >-----Original Message----- >From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On >Behalf Of Sri h Kolusu >Sent: Monday, July 3, 2023 12:28 PM >To: IBM-MAIN@LISTSERV.UA.EDU >Subject: Re: SORTWK space usage > >>>I will only get the primary space of 5000 cylinders, and the other 14x2000 >>>cylinders is never used. Is that right? > >Billy, > >No. Incorrect. DFSORT will make use of BOTH primary and secondary space >allocations ( 1 primary + 15 Secondary) for a total of 16 extents. So if you >allocated 1 sortwk dataset with (CYL,(5000,2000)), then DFSORT would use 5000 >+ 15* 2000 = 5000 + 30000 = 35,000 cylinders. Also note that the secondary >extents will only come into picture ONLY when needed. > >>>Is there a written explanation I can forward to the programmers so they >>>understand this? >>>Also (since I know it will come), is there any good way to calculate how >>>much DASD sortwork would be used? I know this depends on what is in memory >>>at the time, but want to get a better handle on how Sort determines what it >>>needs. > >I would suggest that you use DFSORT's Dynamic Allocation as it will allocate >the required workspace optimally rather than programmers calculating it. The >reason is you don't want to change the allocation every time there is an >increase/decrease in the number of records to be sorted. > >Having said that, here is a general formula that you want to use. > >The amount of sortwk space required depends on the size of the file. It >usually ranges from 1.3X to 1.8X of the size of the file to be sorted >depending on the sorting path that DFSORT chose. > >Filesize = Number of records * Avg length of the record ( for Fixed >length RECFM=F or FB , it is the LRECL value, or RECFM=V or RECFM=VB is >the average length of the record) > >However, that range is applicable ONLY when the entire file is being sorted >using Disk workspace. DFSORT has the capability of using memory (real and >auxiliary storage) and if it runs out of it, it will then use disk workspace. > > >Thanks, >Kolusu >-- > >This message and any attachments are intended only for the use of the >addressee and may contain information that is privileged and confidential. If >the reader of the message is not the intended recipient or an authorized >representative of the intended recipient, you are hereby notified that any >dissemination of this communication is strictly prohibited. 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