Before performing aggregate recovery, you need to determine the DASD and tape unit resources needed to recover the control file, data files, and user tape data sets. You need an equivalent number of tapes during ARECOVER as were used during ABACKUP, assuming the same technology. You can find this information using the LIST AGGREGATE command. For the most part, this information is determined at the backup site and may have been included in the instruction data set during aggregate backup. See Retrieving the instruction data set.
The DASD space requirements depend in part on the residency of the data sets at the backup site and to which device type they will be recovered.
DASD space requirements are displayed in the ARECOVER activity log, the ABACKUP activity log (if recovered), the ABR record created during the PREPARE step, and in the FSR.
During aggregate backup, user tape data sets with a block size equal to or larger than 32K bytes can be included in the selection data set. User tape data sets with block sizes up to 256K-1 bytes can also be included in the selection data set. DFSMShsm Version 2 Release 10 or a subsequent release is required to recover these data sets. In addition, your tape hardware must be capable of processing these large block sizes.
For more information about the LIST AGGREGATE command, see AGGREGATE: Listing the aggregate backup and recovery activity information.