Migration control data set size

Figure 1 is an example, based on 3390 DASD, of the MCDS size work sheet (also found in DFSMShsm work sheets). An example calculation follows the work sheet.

To calculate the size of the MCDS, you need to know only the number of data sets that you want to migrate.

Note:

VSAM extended addressability capabilities allow each MCDS cluster to exceed the 4 GB size. In addition, the MCDS can span up to four unique KSDS clusters. For more information about using VSAM extended addressability capabilities, see Using VSAM extended addressability capabilities. For more information about using KSDS clusters, see Using multicluster control data sets.
If Fast Subsequent Migration is activated via SETSYS TAPEMIGRATION(RECONNECT(ALL)) or SETSYS TAPEMIGRATION(RECONNECT(ML2DIRECTEDONLY)), MCD records are kept longer in the MCDS.