Boy this takes me back - to the Summer of 1990. :-) At the time what I call "The Coffee Table Book" aka the Data In Memory Performance Studies WSC Orange Book was freshish out.
One of the studies was VIO to Expanded Storage. It showed CPU cost across the range of data set sizes, relative to disk. Now, it's 26 years on and it was a while back reimplemented in Central Storage. But I worry it's still CPU-wise expensive. On the other hand memory is MUCH cheaper now. So I doubt customers are really sending all small temp data sets to VIO in CS. (Maybe to VIO.) In the late 1980s we did a lot of work with my customer (Lloyds Bank) to manage VIO with DFSMS and VIOMAXSIZE. And also with Expanded Storage Criterion Ages (ESCTVIO). Out of it came my first widely-propagated presentation: "VIO To Expanded Storage". Sadly I don't have a copy. I'd be pleasantly surprised if someone had a copy (and sent it to me). Much of what I wrote then appeared in 1995 Redbook "Parallel Sysplex Batch Performance" (SG24-2557). Happy days. :-) Cheers, Martin Sent from my iPad > On 2 May 2016, at 21:04, Ron Hawkins <[email protected]> wrote: > > 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 >Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
