Skip, VIO is still a great way to handle small, temp data sets. I've used the method mentioned below where VLF was no help, and LLA Freeze a hindrance, and it works surprisingly well. At less than 1Mb per CYL it’s far from being expensive. Then again, I was a big fan of VFETCH too... Not unlike building a custom LSR pool just for one problematic file.
I'm pretty sure the majority of shops are using DFSMS to limit and direct small allocations to VIO. None of that nasty IO - in and out like the Flash. The best IO is the one you don't do, so why bother with all that VTOC IO just to create and delete a one track data set that you may or may not write to? 20MB (~25 Cyls) is a fairly reasonable max vio size limit, but being a lab I have coded special cases in the ACS routines where I let 0.5GB into VIO. It's nice when I'm in control of 100% of what is running. Ron -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Jesse 1 Robinson Sent: Thursday, April 28, 2016 3:45 PM To: [email protected] Subject: Re: [IBM-MAIN] PDS I/O Performance Improvement Since DASD has become so fast, many shops--including ours--long ago dropped VIO processing. A VIO request simply goes to a SYSALLDA volume. In any case, VIO would be very expensive way to improve performance of a very large data set. . . . J.O.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 323-715-0595 Mobile 626-302-7535 Office [email protected] -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Dana Mitchell Sent: Thursday, April 28, 2016 7:34 AM To: [email protected] Subject: (External):Re: PDS I/O Performance Improvement Wow! flashback from the 80's! We had a CICS region, seriously storage constrained with huge COBOL programs, it would do storage compressions multiple times a minute. A temporary performance boost came from copying the main loadlib into VIO dataset at starup. Dana On Thu, 28 Apr 2016 14:22:37 +0100, Martin Packer <[email protected]> wrote: >If it's a matter of repeated reading why not copy to VIO in Central >Storage and read from there? ---------------------------------------------------------------------- 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
