Storage Groups

You can use Storage Group object options to create, template, alter, and drop DB2 storage groups. A storage group is a DB2 object that represents a named set of DASD volumes controlled by a specified VSAM catalog (VCAT), on which DB2:
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You can use Storage Group object options to create, template, alter, and drop DB2 storage groups. A storage group is a DB2 object that represents a named set of DASD volumes controlled by a specified VSAM catalog (VCAT), on which DB2:
  • Allocates storage for tablespaces and indexes
  • Defines the necessary VSAM data sets
  • Extends and deletes VSAM data sets as required
DB2 monitors and maintains the storage groups, and uses them to store DB2 table and indexspaces. A storage group can be assigned to a database, tablespace, or index space. All tables that reside in a given tablespace use that tablespace's storage group. Following are some of the ways DB2 helps manage external storage requirements.
  • When a tablespace is created, DB2 uses VSAM access method services to define the necessary VSAM data sets. After the data sets have been created, they can be processed with access method service commands that support VSAM control-interval (CI) processing.
  • When a tablespace is dropped, DB2 automatically deletes the associated data sets.
  • When a data set in a simple tablespace reaches its maximum size of 2 GB, DB2 can automatically create a new data set.
  • When needed, DB2 can extend individual data sets.
There are many useful features that are available from within the Storage Group object panels to help you facilitate the creation and overall management of your DB2 storage groups. These features include:
  • Object Selection
    . You can enter selection criteria in many fields to bring up lists of objects to choose from. These fields include VCAT and the VOLSER list. When entering and managing the volumes for your storage group in the VOLSER list, you can use any standard ISPF editor commands to copy, replicate, delete, and move volumes within the VOLSER list. To provide a larger work area for managing the volumes, you can turn the header (top portion of the panel before the VOLSER list) OFF with the HEADER command.
  • Volume and VCAT Selection Help
    . When defining a storage group, the names of the volumes or VCAT that the storage group references must be entered. Instead of having to remember and enter specific volume and VCAT names, they can be selected by entering selection criteria to receive a list of volumes or VCATs.
  • Line Commands
    . Insert and Delete line commands are supported to assist in manipulating the volume list.
  • Primary Commands
    . The following panel-specific primary commands are available to help manage storage groups:
    • Apply Def (apply user defaults to the table definition)
    • Compare (display the original and current object definitions)
    • Header (toggle the display of the panel header fields on or off)
    • Reset (reset all fields to their original values)
    • Source (set all new fields to source field values)
    • Target (set all new fields to target field values)
    The source and target primary commands are only valid in 
    CA RC/Migrator™ for DB2 for z/OS
    . To display the available panel commands, enter a question mark (?) in the primary command line.
  • Template Option
    . The Template option permits creation of a new storage group, using an existing storage group as a model. Enter selection criteria to receive a more specific list of storage groups.
  • Alter Option
    . The Alter Storage Group option lets you change any characteristic of the storage group. While DB2 allows only the addition or removal of volumes from the storage group, we let you change the VCAT or even the storage group name. This is done by dropping, and then recreating the storage group. Like the Template function, the Alter function lets you select from lists of storage groups, VCATs, and volumes.