Data Facility Storage Management Subsystem[a] (DFSMS) is a central component of IBM's flagship operating system z/OS.
On April 19, 1988, IBM announced[9] the umbrella term Data Facility Storage Management Subsystem for facilities provided by the programs In addition to replacing part of the device support in the base MVS/SP, DFP replaces the Linkage Editor and several utility programs and service aids.
DFP is no longer available as a separate product, but has become part of Data Facility Storage Management Subsystem, under the name DFSMSdfp.
DSDSS and DFHSM became optional chargeable features of DFSMS; DFSORT and RACF remained separate products.
DSS replaces the older DASDR and the dump/restore facilities of IEHDASDR, although the dump formats are not compatible.
DFSMSdfp[e] replaces the older direct, index and sequential access methods, the utilities and service aids, the linkage editor, the loader and program fetch.
Partitoned Data Set Extended (PDSE) is a new type of dataset that resolves several issues with the old PDS organization but that can be read and written by existing BPAM, BSAM and QSAM code.
A common scenario is for the installation to write a storage group ACS routine to ignore any UNIT parameter and to select the storage group, and to write a DATACLASS ACS rule to assign a dataclass that has default DCB parameters, with both making decisions based on the data set name.
When SMS is active, several new parameters are available in dynamic allocation and the DD JCL statement, e.g., DSNTYPE.
DFSMSdfp provides facilities for using several different protocols to duplicate or mirror DASD volumes to a remote location.