Advanced Topics › CTCDASD as the Initial Communication Method › How You Implement the CTCDASD Communication Method

How You Implement the CTCDASD Communication Method

To implement the CTCDASD communication method, you customize certain parameters in the MIMINIT member.

Follow these steps:

1. Define the systems participating in the MIMplex using the following DEFSYS statements:

   DEFSYS(sysa,aa,sysa)
   DEFSYS(sysb,bb,sysb)
   

2. To specify preferred master systems and recovery options use the GLOBALVALUE statement.
3. Define the CTC devices for CA MIM communication using the following CTCPATH statements:

   CTCPATH FROMSYSTEM=sysa ADDRESS=deviceaddress TOSYSTEM=sysb
   CTCPATH FROMSYSTEM=sysb ADDRESS=deviceaddress TOSYSTEM=sysa
   

4. Specify CTCDASD as the initial communications method using the MIMINIT COMMUNICATION statement:

   MIMINIT COMMUNICATION=(CTCDASD,INITIAL=[CTC|DASD])
   

   Note: The INITIAL parameter is unique to the CTCDASD communication method. It indicates your preferred communication method. After the synchronization has completed on the DASD or the coupling facility structure control file, this value determines which communication method to employ:

   • INITIAL=CTC indicates CA MIM is to automatically migrate to a selected VCF master.
   • INITIAL=DASD indicates CA MIM is to continue using the DASD or coupling facility structure control file. If desired, the MIGRATE command can be issued later to migrate to a master VCF system.

   This value is checked after the initial DASD or coupling facility structure control file synchronization, and after any event causing a DASD or coupling facility structure control file resynchronization.

5. Define the control files CA MIM will use using the ALLOCATE statement.

Note: For more information, see the CA MIM Statement and Command Reference Guide.