Optimizing Statistics Files

Use this information to determine the most efficient use of Statistics file space.

About this task

Note: IBM® Connect:Direct® does not support extended-format, extended-addressing ESDS Statistics data sets.

In this example, the IBM Connect:Direct software is installed using the default statistics installation of two file pairs with a total capacity of 13,500 records. After running IBM Connect:Direct for a time, you determine that the records log for about 2.5 days before the file pair list wraps. The administrator wants to provide space for 7 days worth of records to be available at any given time. The administrator does the following:

Procedure

  1. Use DGASSTAT to determine the number of records written daily.

    Run the DGASSTAT utility against the statistics entry-sequenced clusters to determine the rate at which the system generates the statistics records.

    For example, DGASSTAT shows that records per day is approximately equal to 5,400.

  2. Determine the total capacity of the statistics file.
    capacity = (records per day) * days

    Determine the total capacity in this example by multiplying the 5,400 records per day by seven days. In this case, the total capacity of the statistics file is 37,800 records.

  3. Determine the number of records per file pair.

    In this example, the administrator decides to define four file pairs, so each are given a capacity of 9,500 records, for a total capacity of 38,000 records.

  4. Determine the RECORDS parameter value for the key-sequenced clusters.
    The number of KSDS records needed depends on both the number of records in the associated ESDS and a factor determined by the ESDS CISIZE. For more information, see Statistic File Recommendation, IBM Connect:Direct for z/OS Configuration Guide. Assume the factor in this case is 0.75 which corresponds to an ESDS CISIZE of 8K.
    KSDS-records = 0.75 * (ESDS-records)

    Determine the number of KSDS records by multiplying 75% by 9,500, the number of records per file pair. The RECORDS parameter value for the key-sequenced clusters is 7,125.

Results

Based on these calculations, the administrator allocates four file pairs. The entry-sequenced cluster (ESDS) of each pair is defined with RECORDS(9500). The key-sequenced clusters (KSDS) are defined with RECORDS(7125).