DB2 11 z/os - DSG Coexistance using V11 Libraries

Jorg Lueke

DB2 11 z/os - DSG Coexistance using V11 Libraries

We have a system that's datasharing with the logon / connections to DB2 happening via the link list DSN that is shared across the LPARS

So member 1 goes to V11, member 2 stays on V10 on a different LPAR. So far so good. If we don't IPL the linklist modules are V10 which should keep connecting. 

https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/inst/src/tpc/db2z_dsharerelcoexist.html

System 1 is IPL'd the link list now has the V11 mods. The shared dataset loaded to the link list can also be steplibed. If that were done and the jobs run against the V10 system would they fail? This would be utilities or TSO batch jobs.

System 2 is upgraded and the IPL / link list refresh follows everything is on 11.

I was thinking, would there be a case where someone tries to log on to the V10 system with the V11 libs and what would happen. Say System 2 crashes, comes up with the refreshed linklist while the DB2 member is still on V10.

I also read this https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/inst/src/tpc/db2z_mixedreleasedsgroup.html

It's clear we can go with the old version to the new. The other way around is probably a no but is that written down?

Jorg Lueke

RE: DB2 11 z/os - DSG Coexistance using V11 Libraries
(in response to Jorg Lueke)

For me the key piece is the following

After you migrate completely to the latest level of Db2, you must update those procedures and jobs to point to the latest level of Db2 load libraries. If you forget to update those procedures and jobs before migrating to any release subsequent to Db2 11, those procedures and jobs can no longer work in that subsequent release.

It seems like the best sequence then is migrate member 1, migrate member 2, IPL system 1, IPL system 2.

The DB2 subsystem and batch jobs use steplibs. The TSO, RRSAF, MQ, and CICS connections use DSNHDECP nad the LOADLIB in the link list. Which, based on this, the V10 version should work swimmingly so long as we don't keep it around for V12. 

James Campbell

DB2 11 z/os - DSG Coexistance using V11 Libraries
(in response to Jorg Lueke)
SDSNLOAD in client-side code is designed to work with one-version-down and and
one-version-up DB2 systems - provided any compatibility PTFs have been applied.

The one got-ya is that utility modules are version specific and need to be present in the
client side SDSNLOAD. But as their names are version specific there isn't a conflict.

Note that the JCL at the bottom of
https://www.ibm.com/support/knowledgecenter/SSEPEK_11.0.0/inst/src/tpc/db2z_recommen
dsforutils.html
copies the V11 utility modules to the V10 SDSNLOAD, and the V10 modules into the V11
SDSNLOAD.

The "<-- add any utility-dependent modules here" modules are DSNU10Lx and DSNU11Lx.
For V12, there aren't any DSNU12xx modules - just DSNUT121

"Say System 2 crashes, comes up with the refreshed linklist while the DB2 member is still
on V10." Provided the linklist has the DSNUT101 and DSNU10Lx modules all will be well.

James Campbell.

On 27 Oct 2017 at 8:32, Jorg Lueke wrote:

>
> We have a system that's datasharing with the logon / connections to DB2 happening via the link
> list DSN that is shared across the LPARS
> So member 1 goes to V11, member 2 stays on V10 on a different LPAR. So far so good. If we
> don't IPL the linklist modules are V10 which should keep connecting. 
> https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/inst/src/tpc/db2z_dsharerelco
> exist.html
> System 1 is IPL'd the link list now has the V11 mods. The shared dataset loaded to the link list
> can also be steplibed. If that were done and the jobs run against the V10 system would they fail?
> This would be utilities or TSO batch jobs.
> System 2 is upgraded and the IPL / link list refresh follows everything is on 11.
> I was thinking, would there be a case where someone tries to log on to the V10 system with the
> V11 libs and what would happen. Say System 2 crashes, comes up with the refreshed linklist
> while the DB2 member is still on V10.
> I also read
> this https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/inst/src/tpc/db2z_mixedre
> leasedsgroup.html
> It's clear we can go with the old version to the new. The other way around is probably a no but is
> that written down?
>

Jorg Lueke

RE: DB2 11 z/os - DSG Coexistance using V11 Libraries
(in response to Jorg Lueke)

Thank you for the clarification, the manual is more precise about 10 to 11 and less so about 11 to 10.