Peter, Spanned records on VSAM are not the same as DSORG=PS.
I need to verify this, but my memory says that even with spanned records, VSAM will write a record in a new CI if it will not fit in the current CI. I thought that spanned records are only written when the record is greater than the CISZ. That means spanned records space efficiency with VSAM depends on the number of records greater than the CISZ. I think that is why it is good for SMF ESDS. Ron -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Peter Vander Woude Sent: Wednesday, January 17, 2018 6:43 AM To: [email protected] Subject: Re: [IBM-MAIN] VSAM Performance - CPU reduction Arun, In the IDCAMS listing, I see that the files are defined NONSPANNED. With the records being variable length, you could have as few as 2 records per ci, since the max is around 11000. if all the records are the minimum of 170, then you would have around 156 records per ci. Have you looked at changing NONSPANNED to SPANNED? That will allow variable length records to go across CI's, and might help in some small way, by decreasing the actual space that the files use up. As such the # of records read in, as defined by the BUFND, will be higher. for the skip sequential file, if you are doing a point and then read next, what is the average number of records that are being processed? Having the BUFND so high, if it's only processing a few records in the data component, then you are reading in, and spending higher cpu time, just to throw away those records and read in the next set of ci's. Anytime you reduce the BUFND, of course your EXCP's will go up, as VSAM I/O counts are the number of times it had to read a group of ci's, as opposed to sequential files, where each block counts as an I/O, no matter what BUFNO is set to. Peter ---------------------------------------------------------------------- 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
