Designing the Storage Class Routine for DB2 Data

DB2® database data sets are identified because of the naming conventions of the HLQs and LLQs. Describe the masks for the data sets requiring above average performance and availability in a FILTLIST statement. Assign them a variable name that is tested in the ACS routine logic. Figure 1 shows the filter list for DB2 storage class ACS routine.

Figure 1. FILTLIST Section for DB2 from Storage Class ACS Routine

FILTLIST section for DB2 database data sets.
FILTLIST SPECIAL_USERS       INCLUDE('SYSPROG','STGADMIN','DBA')
FILTLIST VALID_STORAGE_CLASS INCLUDE('BACKUP','CRITICAL','FAST','FASTREAD',
                                     'FASTWRIT','GSPACE','MEDIUM','NONVIO',
                                     'STANDARD','DBCRIT')
/**********************************************************************/
/*             Start of DB2-related FILTLISTs                         */
/**********************************************************************/
FILTLIST DB2                 INCLUDE(%DB*.**)
FILTLIST DB2_PROD_DIRECTRY   INCLUDE(PDB*.*.DSNDB01.**)
FILTLIST DB2_PROD_CATALOG    INCLUDE(PDB*.*.DSNDB06.**)
FILTLIST DB2_PROD_LOG        INCLUDE(PDB*.**.LOG*)
FILTLIST DB2_PROD_BSDS       INCLUDE(PDB*.**.BSDS*)
/**********************************************************************/
/*             End of DB2-related FILTLISTs                           */
/**********************************************************************/

Figure 2 shows the common logic that lets privileged users, such as the database administrator, override SMS allocation decisions or even to allocate the data set as a non-system-managed data set.

Figure 2. Logic to Permit Special Users to Override SMS allocation

  WHEN (&GROUP = &SPECIAL_USERS &&         /*  Permit storage admin., */
        &STORCLAS = &VALID_STORAGE_CLASS)  /*  system programmers,    */
    DO                                     /*  and DBAs to specify    */
      SET &STORCLAS = &STORCLAS            /*  a storage class        */
      EXIT
    END
  WHEN (&GROUP = &SPECIAL_USERS &&         /*   Permit storage admin. */
         &STORCLAS = 'NONSMS')             /*   or data base admin.   */
    DO                                     /*   to create             */
      SET &STORCLAS = ''                   /*   non-system-managed    */
      EXIT                                 /*   data sets             */
    END

Figure 1 shows the logic to assign storage classes to DB2 database data sets. Only production database data sets are assigned specialized services in this routine. The first character of the data set's HLQ denotes whether the data set is production (P), test (T), or end-user (U). The three low-order characters of the HLQ are set to DB2. The DSN mask defined in the FILTLIST section for the data set type describes it in the LLQ.

Based upon the naming conventions, the following is also true:

The first WHEN clause verifies that the data set belongs to a DB2 system by checking the FILTLIST variable, DB2
Each uniquely named data set type is assigned the recommended storage class
Any DB2 production database data set not specifically identified or any test or end-user DB2 database data set, is assigned STANDARD storage services

Example: SELECT section for DB2 from storage class ACS routine

Figure 3. SELECT Section for DB2 from Storage Class ACS Routine

/**********************************************************************/
/*    Start of DB2 Select                                             */
/**********************************************************************/
  WHEN (&DSN = &DB2)                       /*  Select DB2 data sets   */
    DO
      SELECT
        WHEN (&DSN = &DB2_PROD_LOG)        /*  Use fast write for     */
          DO                               /*  active logs            */
            SET &STORCLAS = 'FASTWRIT'
            EXIT
          END
        WHEN (&DSN = &DB2_PROD_CATALOG OR  /*  Dual copy for catalog  */
              &DSN = &DB2_PROD_DIRECTRY OR /*  directory and boot     */
              &DSN = &DB2_PROD_BSDS)       /*  strap data set         */
          DO
            SET &STORCLAS = 'DBCRIT'
            EXIT
          END
      OTHERWISE                            /*  Give all other DB2 data*/
        DO                                 /*  average performance    */
          SET &STORCLAS = 'STANDARD'
          EXIT
        END

      END

    END

Table 1 shows the attributes for the storage classes assigned to database data sets.

Table 1. Storage Classes for Database Data
Attributes	Storage Classes
Name	MEDIUM	FAST	DBCRIT	FASTWRIT
Direct Millisecond Response	10	5	10	5
Direct Bias	—	—	W	W
Sequential Millisecond Response	10	5	10	5
Sequential Bias	—	—	—	W
Availability	STANDARD	STANDARD	CONTINUOUS	STANDARD
Accessibility	STANDARD	CONTINUOUS	CONTINUOUS	CONTINUOUS
Guaranteed Space	NO	NO	NO	NO
Guaranteed Synchronous Write	NO	NO	NO	NO