CREATE STOGROUP

Invocation

This statement can be embedded in an application program or issued interactively. It is an executable statement that can be dynamically prepared only if DYNAMICRULES run behavior is implicitly or explicitly specified.

Authorization

The privilege set that is defined below must include at least one of the following:

• The CREATESG privilege
• SYSADM or SYSCTRL authority

Privilege set: If the statement is embedded in an application program, the privilege set is the privileges that are held by the of the owner of the plan or package. If the application is bound in a trusted context with the ROLE AS OBJECT OWNER clause specified, a role is the owner. Otherwise, an authorization ID is the owner.

If the statement is dynamically prepared, the privilege set is the privileges that are held by the SQL authorization ID of the process unless the process is within a trusted context and the ROLE AS OBJECT OWNER clause is specified. In that case, the privileges set is the privileges that are held by the role that is associated with the primary authorization ID of the process.

Description

stogroup-name

Names the storage group. The name must not identify a storage group that exists at the current server.

VOLUMES(volume-id,...) or VOLUMES('*',...)

Defines the volumes of the storage group. Each volume-id is a volume serial number of a storage volume. The volume serial number can have a maximum of six characters and is specified as an identifier or a string constant.

If the data set that is associated with the storage group is not managed by Storage Management Subsystem (SMS), VOLUMES must be specified. Asterisks are recognized only by SMS. SMS usage is recommended, rather than using DB2® to allocate data to specific volumes. Having DB2 select the volume requires non-SMS usage or assigning an SMS Storage Class with guaranteed space. However, because guaranteed space reduces the benefits of SMS allocation, it is not recommended. If one or more of the DATACLAS, MGMTCLAS, or STORCLAS clauses are specified, VOLUMES can be omitted. If the VOLUMES clause is omitted, the volume selection is controlled by SMS.

If you do choose to use specific volume assignments, additional manual space management must be performed. Free space must be managed for each individual volume to prevent failures during the initial allocation and extension. This process generally requires more time for space management and results in more space shortages. Guaranteed space should be used only where the space needs are relatively small and do not change.

VCAT catalog-name

Identifies the integrated catalog facility catalog for the storage group. You must specify an alias¹ if the name of the integrated catalog facility catalog is longer than 8 characters.

The designated catalog is the one in which entries are placed for the data sets created by DB2 with the aid of the storage group. These are linear VSAM data sets for associated table or index spaces or for their partitions. For each such space or partition, association is made through a USING clause in a CREATE TABLESPACE, CREATE INDEX, ALTER TABLESPACE, or ALTER INDEX statement. For more on the association, see the descriptions of those statements.

Conventions for data set names are given in DB2 Administration Guide. catalog-name is the first qualifier for each data set name.

One or more DB2 subsystems could share integrated catalog facility catalogs with the current server. To avoid the chance of having one of those subsystems attempt to assign the same name to different data sets, select a value for catalog-name that is not used by the other DB2 subsystems.

DATACLAS dc-name

Identifies the name of the SMS data class to associate with the DB2 storage group. The SMS data class name must be from 1-8 characters in length. The SMS storage administrator defines the data class that can be used. DATACLAS must not be specified more than one time.

MGMTCLAS mc-name

Identifies the name of the SMS management class to associate with the DB2 storage group. The SMS management class name must be from 1-8 characters in length. The SMS storage administrator defines the management class that can be used. MGMTCLAS must not be specified more than one time.

STORCLAS sc-name

Identifies the name of the SMS storage class to associate with the DB2 storage group. The SMS storage class name must be from 1-8 characters in length. The SMS storage administrator defines the storage class that can be used. STORCLAS must not be specified more than one time.

Notes

Device types:

When the storage group is used at run time, an error can occur if the volumes in the storage group are of different device types, or if a volume is not available to z/OS® for dynamic allocation of data sets.

When a storage group is used to extend a data set, all volumes in the storage group must be of the same device type as the volumes used when the data set was defined. Otherwise, an extend failure occurs if an attempt is made to extend the data set.

Number of volumes

There is no specific limit on the number of volumes that can be defined for a storage group. However, the maximum number of volumes that can be managed for a storage group is 133.

z/OS imposes a limit on the number of volumes that can be allocated per data set (currently, 59 volumes). For the latest information on that restriction, see z/OS DFSMS Access Method Services for Catalogs.

Storage group owner:

If the statement is embedded in an application program, the owner of the plan or package is the owner of the storage group. If the statement is dynamically prepared, the SQL authorization ID of the process is the owner of the storage group. The owner has the privilege of altering and dropping the storage group.

Specifying volume IDs:

A new storage group must have either specific volume IDs or non-specific volume IDs. You cannot create a storage group that contains a mixture of specific and non-specific volume IDs.

Verifying the existence of volumes and classes: When processing the VOLUMES, DATACLAS, MGMTCLAS, or STORCLAS clauses, DB2 does not check the existence of the volumes or classes or determine the types of devices that are identified or if SMS is active. Later, when the storage group allocates data sets, the list of volumes is passed to Data Facilities (DFSMSdfp) in the physical order of the rows in the SYSIBM.SYSVOLUMES catalog table.

Related information:

• Implementing DB2 storage groups

Examples

   CREATE STOGROUP DSN8G100
     VOLUMES (ABC005,DEF008)
     VCAT DSNCAT;