Creating concurrent tapes for on-site and offsite storage

The DFSMShsm duplex tape function provides an alternative to TAPECOPY processing for backup and migration cartridge tapes. This option allows you to create two tapes concurrently: the original tape can be kept on-site while the alternate tape can be taken offsite or written to a remote tape library. The pair of tapes always maintain an "original versus alternate" distinction. The original cartridge-type tape volume will have one of the following data set names:

prefix.HMIGTAPE.DATASET
prefix.BACKTAPE.DATASET

while the alternate cartridge-type tape volume will have one of the following data set names:

prefix.COPY.HMIGTAPE.DATASET
prefix.COPY.BACKTAPE.DATASET

These data set name formats allow the new tapes to remain compatible with the current tapes created by the TAPECOPY command.

Within an SMS environment, ACS routines can direct the alternate tape to a different tape library, such as one at an offsite location. Within a non-SMS environment, the output restricter (for example, SETSYS UNIT(3590)) is used for both the original and the alternate. If allocation routing separation is needed, it must be done outside of DFSMShsm. Alternate tapes must keep the same tape geometry as the original tape (for example, both must be 3590 standard length tapes). For those customers who are drive-constrained, DFSMShsm maintains the existing TAPECOPY creation methods.