Availability management considerations for extended SAM and extended and compressed VSAM data sets

When DFSMShsm does backup and recovery processing for extended format SAM and VSAM compressed data sets, be aware of the following results:

• When DFSMShsm backs up an extended format VSAM compressed data set, it recovers that data set only as an extended format compressed data set.
• When DFSMShsm backs up an extended format SAM compressed data set, it recovers that data set as either an extended format compressed or nonextended format SAM data set.
• When DFSMShsm backs up a compressed SAM or VSAM data set, it suspends software compression for that data set.
• When a compressed SAM or VSAM data set is backed up, DFSMShsm records in the BCDS that it is a compressed data set. It also records both the compressed size of the data set and the size the data set would be if it were not compressed. This information is passed to DCOLLECT.