The Estimate Report—DASD Buffer Cost Breakdown

The tape mount management DASD Buffer Cost Breakdown provides the details for the DASD buffer costs in the Savings/Cost Summary (Figure 1). This breakdown report shows the distribution of data sets by tape mount management data set category and the way they will reside in the simulated target environment.

Figure 1 is the third breakdown report. All the values in this report represent weighted averages based on the number of days the data sets resided on the various levels of storage. For example, a data set with 500 tracks has a size of 15MB on migration level 2. If it resides on migration level 2 for two thirds of the sample, the DASD Buffer Cost Breakdown shows it having a value of 10MB.

Figure 1. Estimate Report—DASD Buffer Cost Breakdown

                                           GFTASRT3 -- ESTIMATE REPORT --  33 DAY SAMPLE

                                                              11 
+-------------------------------------------------------------------------------------------------------+
|                                  DASD BUFFER COST BREAKDOWN                                           |
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| DATA SET |      |  ORIGINAL|  ORIGINAL|DFSMS - PRIMARY| HSM  - LEVEL 1| HSM  - LEVEL 2| TAPE - DIRECT |
| CATEGORY |  DSN#|   SIZE-MB|   SIZE-TK|  DSN#| SIZE-TK|  DSN#| SIZE-TK|  DSN#| SIZE-MB|  DSN#| SIZE-MB|
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| TEMPORARY|   141|      3039|     83217|     6|     659|      |        |      |        |      |        |
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| ACTIVE   |   200|      6779|    196782|    29|   33999|     0|       0|   171|    3942|      |        |   12 
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| ACTV GDG |  1685|     71285|   1977258|   104|  120649|     0|       0|  1581|   52769|      |        |
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| BACKUP   | 38794|    761995|  20359815|  2030| 1095199|      |        | 36764|  451926|      |        |
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| LARGE    |   418|    466686|  14200124|      |        |      |        |      |        |   418|  203378|   13 
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| HSM SFF  |     0|         0|         0|      |        |      |        |      |        |     0|       0|
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| HSM GEN  |     0|         0|         0|      |        |      |        |      |        |     0|       0|
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| MGMTCLAS |      |          |          |      |  103622|      |       0|      |    1689|      |        |   14 
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
| T O T A L| 41238|   1309784|  36817196|  2169| 1354128|     0|       0| 38516|  506948|   418|  203378|
+----------+------+----------+----------+------+--------+------+--------+------+--------+------+--------+
                                                              15

11 In some cases, the HSM LEVEL 1 SIZE-TK column might contain values even if the HSM LEVEL 1 DSN# values are zero. If data has resided on migration level 1 at some time during this sample, there could be zeros in the DSN# column and values for the number of tracks used in the SIZE-TK column.

12 There are 1885 active data sets in this sample, 200 non-GDG data sets and 1685 GDG data sets. Based on the keywords specified or defaulted (see Estimating Savings and Costs) in this GFTAVMA run, 29 of the active non-GDSs would reside on the tape mount management DASD buffer (DFSMS DSN# PRIMARY SIZE-TK) while 171 of them would have already migrated to migration level 2 tape (HSM LEVEL 2 DSN#).

13 The TAPE DIRECT column shows the LARGE data sets, which DFSMS would not intercept, but would write directly to tape. In this case, 418 data sets are greater than the LARGE keyword value, so they would be modelled as going directly to tape. The size reduction from 466686MB to 203378MB would be a result of IDRCFACTOR of 3, TAPEDEV of 3490E, and TAPELEN of 2.

14 The MGMTCLAS row shows the data set recall activity caused by your selection of LEVEL0AGE and LEVEL1AGE. You can reduce the recall mounts by changing the values for L0AGE and L1AGE. See The Management Class Report for details on changing values.

15 In this example, the volume mount analyzer simulates an environment where DFSMShsm bypasses migration level 1 processing. Therefore, the columns for migration level 1 contain zeros. The data sets go directly from primary DASD to migration level 2 tape, bypassing migration level 1 DASD because the LEVEL0AGE and LEVEL1AGE keywords defaulted to one.

If the L1AGE value is greater than L0AGE (for example, L0AGE=1 and L1AGE=3), then the data sets that are not referenced would reside on primary DASD for one day, then migrate to migration level 1 DASD and reside for an additional two days, and finally migrate to migration level 2 tape. They would go to migration level 2 tape after a total of three days since the data sets were last referenced.