11. WORKLOAD CHARACTERIZATION › 11.6 Case Studies › 11.6.3 IMS Transaction

11.6.3 IMS Transaction

To investigate potential IMS transaction classes, we used
Workload Characterization to analyze DETAIL IMS transaction
data collected with the optional _USRXISU exit in the IMS
Component.  In particular, we analyzed the IMS transaction
data to determine patterns based on CPU time, message queue
calls, and database calls.

To identify potential IMS transaction classes, we analyzed
the DETAIL timespan IMSISU File.  (The IMSISU File is not
normally supported in the DETAIL timespan, but was included
through the use of an optional exit.)

We specified three data elements on the Workload
Characterization screen:

    ISUCPUTM - The CPU time consumed by the transaction

    ISUDBTOT - The total number of database calls issued by
               the transaction

    ISUMSTOT - The total number of message queue calls issued
               by the transaction

We selected four data elements as reporting variables:

    ISUDBGU -  The number of database GET UNIQUEs issued by
               the transaction

    ISUDBGN -  The number of database GET NEXTs issued by
               the transaction

    ISUMSGET - The number of message queue GET UNIQUE and GET
               NEXTs issued by the transaction.  This value
               is computed from ISUMSGGU and ISUMSGGN.

    ISUCPUTM - The CPU time consumed by the transaction

The centroids of the six clusters that we developed are shown
in Figure 11-33.  Cluster 2 represents 71% of the
transactions that were processed.  We could potentially use
the transactions in this cluster to define an IMS transaction
class.  However, we would have to perform further analysis on
the ALL_OBS SAS data set to verify that the DBD requirements
of the transactions do not conflict (ART78, LEE83).


                              CLUSTER CENTROIDS

CLUSTER  ISUCPUTM  ISUDBTOT  ISUMSTOT  RADIUS  NO ASSIGN  PCT
-------  --------  --------  --------  ------  ---------  ---
   1         0.13      11.9      1.23    1.00      219     11
   2         0.21       9.8      2.99    1.00     1423     71
   3         0.17      17.8       0.5    1.00       77      4
   4         1.13     150.3       1.0    2.00       41      2
   5         0.85       1.3      61.2    1.50      137      7
   6         0.53       0.9       0.1    1.00      103      5


 Figure 11-33.  IMS Cluster Centroids Report