The Estimate Report Legend—Explanation of Symbols

The Estimate Report legend shows the specified and defaulted keywords that were used to produce the Estimate Report. It also defines the tape mount management data set categories and shows how DFSMS would manage the data sets in each of those categories in the simulated environment. See Categories of Tape Mount Management Data Sets for more information about the various categories of data.

Figure 1 is the legend for this example Estimate Report. It explains the assumptions GFTAVMA used when calculating the numbers for the Estimate Report. This legend shows how GFTAVMA determines which data sets would be migrated to which storage levels.

Figure 1. The Estimate Report Legend

*********************************************************************************************************
*                                                                                                       *
*          TARGET DEVICES:            FREE SPACE:                                                       *
*                 DASDDEV = 3390-3           FSPACE = 5%                                                *
*                 TAPEDEV = 3490E          L1FSPACE = 5%                                                *   16 
*                 TAPELEN =  2                                                                          *
*                                                                                                       *
*          TAPE MOUNT MANAGEMENT CATEGORIES:                                                            *
*                   +-----------+                                                                       *
*                   | TEMPORARY | --> LEVEL 0 DASD AND EXPIRE AFTER USAGE                               *
*                   +-----------+                                                                       *
*                   | ACTIVE +  | --> LEVEL0AGE =   1 DAYS                                              *
*                   | ACTV GDG  |     LEVEL1AGE =   1 DAYS                                              *
*                   +-----------+                                                                       *   17 
*                   |  BACKUP   | --> LEVEL 2 AFTER 0 DAYS (IF MIGRATION RUNS ONCE EVERY 24 HOURS)      *
*                   +-----------+                                                                       *
*                   | MGMTCLAS  | --> RECALL ACTIVITY FROM LEVEL0AGE AND LEVEL1AGE VALUES               *
*                   +-----------+                                                                       *
*                                                                                                       *
*          DATA SETS ==> DIRECTLY TO TAPE:                                                              *
*                   +-----------+                                                                       *
*                   |  LARGE    | --> DATA SETS >    600 MB                                             *
*                   +-----------+                                                                       *
*                   | HSM SFF   | --> HSM SINGLE-FILE FORMAT DATA SETS                                  *   18 
*                   +-----------+                                                                       *
*                   | HSM GEN   | --> HSM-GENERATED DATA SETS                                           *
*                   +-----------+                                                                       *
*                                                                                                       *
*********************************************************************************************************

16 The DASDDEV keyword specifies the DASD device that GFTAVMA should use as the model for the tape mount management DASD buffer, which in this example defaulted to the DASDDEV value of 3380E.

GFTAVMA modelled to the 3490E with Enhanced Capacity Cartridge System Tape because a TAPEDEV of 3490E and a TAPELEN of 2 were specified.

When GFTAVMA models the tape mount management DASD buffer, it uses a high free space threshold as DFSMShsm would. The GFTAVMA defaults are 5% free space on the primary DASD buffer and 5% free space on the migration level 1 buffer. If you wish to change these free space percentages, use the FSPACE and L1FSPACE keywords.

17 The tape mount management data set categories section shows when DFSMS would migrate data sets from primary storage to migration level 1 to migration level 2:

Temporary data sets reside on primary DASD for the duration of the job and then expire, so they never migrate.
Active data sets and active GDG data sets are controlled by the LEVEL0AGE and LEVEL1AGE values of 1, so these data sets would reside on primary storage for one day before migrating to migration level 2 tape (if the data sets are not referenced during this time).
Backup data sets migrate to migration level 2 tape after zero days if migration runs every 24 hours. Backup data sets would reside on primary storage for less than one day. They would never reside on migration level 1 regardless of the values for L0AGE and L1AGE.
MGMTCLAS data sets are data sets that have recall activity. They are recalled from migration level 2 and migration level 1 back to primary storage. The recall activity is based on the last reference to the data set, which is calculated by GFTAXTR, and on the values specified by the LEVEL0AGE and LEVEL1AGE keywords.

You need to select management class reference ages for active data sets that would migrate the data at optimum times. In this example, L0AGE and L1AGE defaulted to 1, but these might not be the optimum values based on the data set usage at your installation. The Management Class Report can help you determine the recommended values to use for each application. See The Management Class Report.

For the Estimate Report, GFTAVMA assumes you specified the migration level 1 compaction value that you feel you can achieve using the DFSMShsm level 1 compaction option. The default is 50% compaction, which means migration level 1 is reduced by 50% from primary storage. The Estimate Report example in this section shows 50% compaction, but you can use the COMPACTION keyword to change that percentage.

18 GFTAVMA models data sets larger than the LARGE keyword value (default 600MB) as going directly to tape. In this way, DFSMS does not manage them in the storage hierarchy. GFTAVMA also models DFSMShsm SFF and GEN data sets as going directly to tape.