What is needed to implement IBM metro mirroring?

Document ID : KB000015065
Last Modified Date : 20/08/2018
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Question:

We are getting ready to implement IBM metro mirroring.  IBM states that one of the requirements is that all reserves be converted to enqueues.  What is needed to convert the ACF2 Reserve to an ENQ?

Answer:

Sites wanting to convert the ACFVSAM reserve can remove the following line from the GRS exclude list recommendations:

RNLDEF RNL(EXCL) TYPE(GENERIC) QNAME(ACFVSAM) 

This removes the exclusion of ACFVSAM. The EXCLude list means that any resource named is treated as a "local" resource if an ENQ, DEQ, or RESERVE macro instruction specifies a scope of SYSTEMS. 

Removing this entry alone does NOT convert the reserve, that is what the RNLDEF RNL(CON) does. The IBM doc for GDPS (Geographically Dispersed Parallel Sysplex) includes a generic RNL(CON): 

RNLDEF RNL(CON) TYPE(PATTERN) QNAME(*) 

which converts ALL reserves to global enqueues. In this case, only the removal of the ACFVSAM exclude is needed .

The ENQDSN parameter of the CAIACFxx parmlib member can be used to change the enq names. This does not have anything to do with the conversion of the reserve. It allows for multiple systems to be more specific when global enqs are being used. Instead of the ENQ being for ACFVSAM.LOGONIDS it will be for ACFVSAM.name.of.logonids.database . 

If you are only sharing one set of databases you do not need this parameter, if you have multiple database sets that are shared, the ACF2 ENQDSN is recommended.