Thanks for the response - I do have a question about the backwards migration 
PTF. I found conflicting documentation that this is required:

https://www.ibm.com/docs/en/ibm-mq/9.1?topic=tasks-backward-migration-earlier-supported-releases-mq-zos
The backward migration APARs are PI95928 for IBM MQ 8.0.0, and PI95939 for IBM 
MQ 9.0.0.

This was documentation for reverting back from 9.1.   But I seemed to recall 
this same statement from reverting back from 9.2.   
Also found documentation that states nothing needs to be done for backwards 
compatibility from 9.2. 

I also found this:

Backwards migration is normally only performed immediately after a migration 
fails for some reason. 
However, it is possible to perform backwards migration at any time if the 
CSQY039I message is output at queue manager start up.

If a queue manager issues the CSQY040I message at start up, backwards migration 
is not supported, and the procedure described in the following text is not 
applicable.
If you have a back up of the queue manager data, prior to the migration, you 
could use that data to start the queue manager up at the earlier release.

I assume these messages are displayed during start of MQ 9.2 because I don’t 
see these messages in the startup of MQ 9.0. 

Is this correct ?

Thank You 

-----Original Message-----
From: IBM Mainframe Discussion List <[email protected]> On Behalf Of 
Colin Paice
Sent: Wednesday, April 28, 2021 6:06 AM
To: [email protected]
Subject: Re: MQ For z/os

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Mark,

Backwards migration is supported between LTS releases (i.e. 9.0.0, 9.1.0, 
9.2.0), so it's not correct that the upgrade process is not reversible, unless 
the question is about a CD release.

IBM always suggested being up-to-date with all maintenance before migrating to 
a new release. The backwards migration process has changed in 9.2, and there is 
no need to apply a specific backwards migration PTF before migrating. The 
backwards migration process in 9.2 is documented here:
https://www.ibm.com/docs/en/ibm-mq/9.2?topic=92-reverting-queue-manager-previous-version-zos
.

All the MQ on z/OS migration information is documented under this topic:
https://www.ibm.com/docs/en/ibm-mq/9.2?topic=mq-migrating-zos


The question about backing up your page sets and logs is an interesting one.

If you backed up your page sets, and restored a pageset,  (and did not restore 
your logs from backup) then when you restart the queue manager it would replay 
the logs and bring the restored page set(s) up to date.

If you back them up, go to the next release, run for a day and then decide to 
use your backups of page sets AND LOGS ( so your logs now do not have any 
updates since the backup) This causes problems like Messages which had been in 
the system, and processed - now appear again (from the backup) - so where the 
message said "PAY COLIN $1000000" would get processed twice.
Any new messages which were not processed before shutting down and restoring 
would be overwritten by the restore.
Any channels going to other queue managers which had sent messages, will get 
sequence number mismatches and you will have to reset the channels.

So the lesson is, you can ( and should backup) your pages sets, but *do not try 
to restore the logs from backups* except under IBM's guidance.
(As a good sysprog you will have tested the backup and restore of a page set - 
and have JCL already written to do this!)

regards

Colin





If you were on LTS, you could go from 9.0 to 9.1 and back to 9.0 without losing 
any messages.






On Tue, 27 Apr 2021 at 16:52, Steely.Mark <[email protected]> wrote:

> Has anyone upgraded from MQ 9.0 to 9.2 ?
>
> Is there any PTF's that need to be applied to 9.0 before going to 9.2.
> This is the only thing I have found:
>
> While at MQ 9.0, take a full backup of the queue managers. Why? 
> Because the upgrade process is NOT reversible. If you need to revert 
> back from MQ
> 9.1 to 9.0, then you must delete the queue managers and restore the 
> backup taken at MQ 9.0.
>
> I know this statement is talking about 9.1 but I think it would also 
> relate going to 9.2.
>
> Any information relating to upgrading MQ would be appreciated.
>
> Thank You
>
>
>
>
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