When DFSMShsm does space management on a volume, it maintains data
set integrity by processing only data sets that meet a certain
integrity age. This integrity age specifies the
minimum time that must elapse since the data set was last used before
the data set can be processed by space management. The integrity age
is affected by the DFSMShsm host environment and by the method of
serialization.
Note: A multiple DFSMShsm-host environment
is determined by DFSMShsm at startup time by examining whether the
index component of the migration control data set resides on a DASD
volume that has been SYSGEN’d as SHARED or SHAREDUP. If this is
the case, DFSMShsm performs what is called multiple
host serialization.
Integrity age is established as follows:
- If serialization is DFHSMDATASETSERIALIZATION and the processing
environment is a single DFSMShsm-host environment, the integrity age
is one day.
- If serialization is DFHSMDATASETSERIALIZATION and the processing
environment is a multiple DFSMShsm-host environment, the integrity
age is two days.
- If serialization is USERDATASETSERIALIZATION, the integrity age
is zero days.
- For temporary SMS-managed data sets in a JES3 environment, the
integrity age is two days.