If a data set that has migrated is needed for processing, DFSMShsm
recalls the data set from the migration volume on which it resides
to an SMS-managed volume. The storage management subsystem selects
the SMS-managed volume to which the data set is returned. Migrated
extended format VSAM data sets can be recalled only as extended format
VSAM data sets. Migrated extended format sequential access method
(SAM) data sets can be recalled as extended format or nonextended
format data sets.
If a data set is assigned to a management class
with no defined transition, then the allocation will be performed
using the standard ACS routines.
If a data set is assigned to a management class
with a defined transition, then the allocation will be done as follows:
- If the data set has not yet transitioned nor missed a transition,
then the allocation will be performed using the standard ACS routines.
- If the data set had transitioned before being migrated, then the
allocation will be performed using the class transition ACS routines
to ensure that the data set is allocated back to the appropriate level.
- If the data set missed one or more transitions during the period
in which it was migrated, then the allocation will be performed using
the class transition ACS routines. If multiple transitions were missed,
then the class transition ACS routines will be invoked for each transition
that was missed (up to 5 times), to ensure
that the data set is allocated on the appropriate level.
Note: To avoid circularity, DFSMShsm
will limit the number of repeated ACS routine invocations to five.