Not sure when it changed (at least a decade ago), I think the mainframe reads and writes full tracks at a time anymore.
On Wed, Nov 23, 2022 at 7:01 PM Michael Oujesky <[email protected]> wrote: > > Actually, if you are doing sequential processing, zEDC is perhaps the > best as it "write"s full-tracks, regardless of the BLKSIZE > specified. With zEDC, the BLKSIZE is just the size of data passed > to/from the application and no longer the physical data "written" to disk. > > Michael > > At 12:14 PM 11/23/2022, Mike Schwab wrote: > > >If you are doing sequential reads and writes, half track is the best > >you can do. If you are random reading small records, I.E. 80 byte, > >400 bytes, 2000 bytes; then smaller blocks lead to less I/O per > >record, since you aren't using most of the data read, and the larger > >the block the less you use. VSAM use a 4K physical record unless > >you specify a very large CI size. > > > >On Wed, Nov 23, 2022 at 11:56 AM Paul Gorlinsky <[email protected]> > >wrote: > > > > > > Short block more efficient? Elaborate please. Space utilization > > and efficient are not necessarily the same. Latency issues vary a > > lot depending on the exact box being used for DASD. DS6K v DS8K. > > DS8K with rotating v solid-state ... > > > > > > QSAM v BPAM v BSAM v etc... > > > > > > General guidelines ... > > > > > > ---------------------------------------------------------------------- > > > For IBM-MAIN subscribe / signoff / archive access instructions, > > > send email to [email protected] with the message: INFO IBM-MAIN > > > > > > > >-- > >Mike A Schwab, Springfield IL USA > >Where do Forest Rangers go to get away from it all? > > > >---------------------------------------------------------------------- > >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 -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
