DAYS: Specifying the minimum migration age of a data set

Explanation: DAYS(days) is an optional parameter specifying the number of contiguous days a data set must remain unreferenced before the data set is eligible for migration. DFSMShsm uses this parameter to migrate data sets from primary volumes to migration level 1 volumes under the following conditions:

The primary volume does not already have a minimum migration age.
- For automatic migration, DFSMShsm checks the minimum migration age you specified with the ADDVOL command. If you did not specify the MIGRATE(days) parameter of the ADDVOL command, or if you specified MIGRATE(0) with the ADDVOL command, or if you specified MIGRATE(1) with the ADDVOL command in a multiple-DFSMShsm-host environment and did not specify USERDATASETSERIALIZATION, then DFSMShsm uses the minimum migration age you specify with the SETSYS DAYS parameter.
- For command migration, DFSMShsm checks the minimum migration age you specified with the MIGRATE command. If you did not specify a value for days with the MIGRATE command, DFSMShsm checks whether you specified the minimum migration age with the ADDVOL command. If you also did not specify the MIGRATE(days) parameter of the ADDVOL command, or you specified MIGRATE(0) with the ADDVOL command, or you specified MIGRATE(1) with the ADDVOL command in a multiple-DFSMShsm-host environment and did not specify USERDATASETSERIALIZATION, then DFSMShsm uses the minimum migration age you specify with the SETSYS DAYS parameter.
For nonmanaged volumes, DFSMShsm checks whether you used the MIGRATE command to specify the minimum migration age. If you did not, DFSMShsm uses the age you specify with this parameter.

The value you specify for days depends on your environment. If USERDATASETSERIALIZATION has been specified, DAYS can be set between 0 and 999. If not, DAYS can be set between 1 and 999 in a single-DFSMShsm-host environment, and between 2 and 999 in a multiple-DFSMShsm-host environment.

SMS relationship: Parameter does not apply to SMS-managed DASD volumes or data sets.

SETSYS default: None.

DFSMShsm default: If you do not specify this parameter on any SETSYS command, the DFSMShsm default is one day if DFSMShsm is running in a single-DFSMShsm-host environment or two days if DFSMShsm is running in a multiple-DFSMShsm-host environment.

Note: DFSMShsm uses the DAYS value when you have not defined thresholds of occupancy for a volume. If you have defined thresholds of occupancy for the volume, the DAYS parameter is another way to set a lower limit for migration.