Through Automatic Class Selection (ACS) routines, SMS assigns classes to data based on its requirements and attributes and select specific storage groups to store the data. In order to do this, SMS (Storage Management System) uses classes and groups that are associated or assigned to data sets, objects and volumes.
Types of SMS classes and Groups
|Data Class||Data definition parameters – collection of allocation and space attributes that the system uses when creating a data set|
|Storage Class||Availability and accessibility requirements. It provides the criteria that SMS uses in determining an appropriate location to place a data set or object. SMS uses the storage class to select a device according to the following criteria: device performance, the amount of space available on the volume, and how available a data set or object can be on that device.|
|Management Class||Data migration, backup, and retention attributes. For data sets, these attributes control retention, migration, backup, and release of allocated but unused space. For OAM objects, the attributes control retention, backup, and class transition.|
|Storage Group||List of storage volumes with common properties. It can be collections of DASD volumes, volumes in tape libraries or in optical libraries, or virtual input/output (VIO) storage.|
|Aggregate Group||Backup or recovery of all data sets in a group in a single operation. An aggregate group is a collection of user-defined data sets that are processed together such as the collection of data sets used for a payroll program. DFSMShsm can back up and recover aggregate groups. A storage administrator might group related data sets in this manner:
|Copy Pool||A pool of storage groups to be processed collectively for fast replication operations|