If I understand the details: First copy operation read a whole bunch of smallish blocks and wrote out SDB blocks at 2/track. Lots of overhead on reads, much less so on writes. I would expect this result.
Second copy operation both read and wrote SDB blocks, so minimal overhead on both sides. I would expect this result. . . J.O.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 323-715-0595 Mobile 626-543-6132 Office ⇐=== NEW [email protected] -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Mike Schwab Sent: Tuesday, May 23, 2017 3:00 PM To: [email protected] Subject: (External):Re: SDB (system determined Blksize) About a dozen copies at 1/2 track block size vs `1 copy from small block size to 1/2 track in the same elapsed time. On Tue, May 23, 2017 at 8:14 AM, Charles Mills <[email protected]> wrote: >> The subsequent several copies ran much faster and also took about 10 minutes. > > But it was a much faster 10 minutes? > > Charles > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] > On Behalf Of Mike Schwab > Sent: Monday, May 22, 2017 10:08 PM > To: [email protected] > Subject: Re: SDB (system determined Blksize) > > Every time you deal with a block you execute a bit of code to deblock the > records. To fill a Mod 9 volumes to test TDMF I copied a large dataset with > a small block size to a dataset with half track blocking on a spare volume, > then copied the first data set to several other datasets to fill the volume. > The first copy to the half track blocksize took about 10 minutes. The > subsequent several copies ran much faster and also took about 10 minutes. > > ---------------------------------------------------------------------- > 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
