Calculating the Number of Cylinders/Tracks - Finalist - 10.0

This section provides instructions for calculating the number of cylinders/tracks required for a given Finalist VSAM cluster. The number of cylinders/tracks required varies according to type of DASD, record size, and control interval size. The actual number of records in the Finalist VSAM clusters also varies slightly with each new update or distribution. Refer to the IBM VSAM Administration Guide to find capacity and physical record sizes by device type.

1. Subtract 8 from the control interval size of the file. Divide this value by the record size (LRECL). The result is the number of logical records per VSAM physical record.
2. Multiply the result from step 1 by the number of physical records that fit on one track. The chart in the IBM VSAM Administration Guide (z/OS users) shows the number of physical records that fit on one track. The result is the total number of VSAM physical records in the file.
3. Divide the total number of records in the file by the result from step 2. The result is the number of tracks required for the file. To find the number of cylinders required, divide the number of tracks required by the number of tracks per cylinder.

1.   4096 (VSAM control interval size)
  -     8 (VSAM overhead)
     4088 (Number of data bytes per physical record)
  /  4088 (Divide by record size)
        1 (Number of logical records per physical record)

2.      1 (Number of logical records per physical record)
  X    12 (Physical records per track for 3390 DASD)
       12 (Number of logical records per track for 3390 DASD)

3.  17479 (Total number of records in the file)
  /    12 (Number of logical records per track for 3390 DASD)
     1457 (Total number of 3390 tracks required)
  /    15 (Tracks per cylinder for 3390)
       98 (Number of cylinders required)