Maybe it's my poor English, but I'm not sure.
Paul Feller in the message below confirmed that autoswitch is working
inside the sysplex. And few sysplexes share VTS installation, but each
of the sysplexes use it's own, statically (manually) assigned set of
devices.
That's what I mean. Indeed, autoswitch between sysplex members is
working with no additional software.
However, David - you wrote, that my understanding is/was good for real
tape drives (standalone), but TS7700 changed the game rules. That means
"foreign" (non-sysplexed) systems can autoswitch virtual tape devices
(with no additional software). Have I understood it correctly?
AFAIK the autoswitch inside sysplex does use/require sysplex
communication. I cannot imagine why the communication is required
between sysplex members, while non-sysplexed z/OS images can autoswitch
devices with no communication.
Exempt from z/OS 3.1 documentation:
With z/OS Release 2 and higher, the ATS STAR design improves the
availability and system management characteristics of the previous
automatic tape switching function. ATS STAR does not use the IEFAUTOS
structure but instead uses global resource serialization and XCF
services to maintain serialization when it allocates shared tape
devices. To maximize the performance of the ATS STAR function, use the
global resource serialization STAR configuration rather than the ring
configuration.
Fun fact: I have found similar discussion in the archives of IBM-MAIN.
It was 20 years ago and I was one of the participants. :-)
A member of DFRMM development suggested IBM ATAM for cross-sysplex.
Of course it was 20 years ago, things could have changed, but I never
heard about such change. I would be happy to find some confirmation
about the change - technical details, chapter in manual, presentation,
anything.
Regards
--
Radoslaw Skorupka
Lodz, Poland
W dniu 30.05.2025 o 14:28, Jousma, David pisze:
Radoslaw, you said: “Yes, autoswitch does not require MIM. However autoswitch
will not work across sysplex boundaries.”
This is not correct with regards to TS7700 series tape libraries. It does
work across sysplex boundaries without additional software. You are correct
with regards to stand alone tape drives I believe. Not sure how much of that
is still around though.
Dave Jousma
Vice President | Director, Technology Engineering
From: IBM Mainframe Discussion List<[email protected]> on behalf of Radoslaw
Skorupka<[email protected]>
Date: Friday, May 30, 2025 at 8:12 AM
To:[email protected] <[email protected]>
Subject: Re: Autoswitch
W dniu 29.05.2025 o 13:58, Jousma, David pisze:
AUTOSWITCH does NOT require GRS/MIM, etc to work inside or outside the sysplex
any longer. We have same tape drives online to 5 different sysplexes.
Again: it is NOT ABOUT GRS/MIM.
Yes, autoswitch does not require MIM. However autoswitch will not work
across sysplex boundaries.
However there are software products which allow it.
Product names are IBM ATAM (Automated Tape Allocation Manager) and CA-MIA.
Both are licensed (and paid) products.
And still, having dozens of virtual drives allow user to assign the
drives statically and forget about the issue.
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