Thanks Ed.
I actually have that MP3000 manual on my PC from when I was using a
MP300. It has more commands than I had in my other best reference.
Wish I had something newer for the DS8000. :-(
Tony Thigpen
Ed Jaffe wrote on 5/11/23 19:47:
On 5/11/2023 3:54 PM, Tony Thigpen wrote:
I don't know if it should be on this list, or IBM-Main, but I am
looking for some good documentation on current command codes used in
CCWs.
For example, I am helping a customer with a issue with VSE cause by a
vendor program that is using a command code of 'A5' and I can't find
A5 in any of my manuals.
I would even be willing to pay some nominal fee to IBM for a
'non-disclosure' document on this subject if needed.
A5 is Write Track Data (WTD), which I first saw described in
SA22-1025-00 (S/390 Internal Disk Subsystem: Reference Guide) back in
2009. Yes, we had a MP3000 back then :-)
Basically, WTD lets you write multiple blocks on a track (or even whole
tracks) with a single CCW. The blocks are usually contiguous in storage
but need not be. You can use MIDAWs (or TIDAWs when using zHPF) to
dynamically change the source data address. There is also A4 Read Track
Data (RTD).
I gave a session twice recently (once for IBM's zExpert series and once
for GSE UK virtual during the pandemic) called "JES3plus I/O
Improvements" where I described how we introduced RTD (and WTD) to
JES3plus as part of our rewrite of JES3's SPOOL I/O. Both sessions were
recorded and should be available for playback.
IBM JES3 was still using early 1990s ECKD until we got hold of it. Now
it can use advanced ECKD (ACKD) or zHPF for shops with modern DASD
hardware. In a SPOOL-I/O intensive benchmark, JES3plus ran approximately
twice as many jobs over the same interval while simultaneously reducing
overall channel utilization by 92 percent! It blew away both IBM JES3
and IBM JES2 in that benchmark!
--
Phoenix Software International
Edward E. Jaffe
831 Parkview Drive North
El Segundo, CA 90245
https://www.phoenixsoftware.com/
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