The point Charles was making (albeit tongue-in-cheek) was that Mike's comment about the second copies was ambiguous. The first time I read it, I had the exact same thought as Charles - it took 10 minutes to do the first copy then each of the following copies took 10 (faster) minutes. When I re-read it, I saw that Mike was meaning that the combined total of the several copies took a total of 10 minutes. I, for one, got a chuckle out of Charles' reply.
Rex -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Jesse 1 Robinson Sent: Tuesday, May 23, 2017 5:12 PM To: [email protected] Subject: Re: SDB (system determined Blksize) 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 The information contained in this message is confidential, protected from disclosure and may be legally privileged. If the reader of this message is not the intended recipient or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any disclosure, distribution, copying, or any action taken or action omitted in reliance on it, is strictly prohibited and may be unlawful. If you have received this communication in error, please notify us immediately by replying to this message and destroy the material in its entirety, whether in electronic or hard copy format. Thank you. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
