Utilities › RMODBASE - Database Maintenance › ADDDS Control Statement › Calculating Cylinders for Your Database

Calculating Cylinders for Your Database

There is no exact method for computing the number of cylinders required for a database. You can, however, use the formula in this section initially to calculate the number of cylinders to set aside for the database.

Note: The amount of space you actually require can vary significantly from the value you calculate. Use the STATUS control statement periodically to determine the actual space you use and adjust the number of cylinders accordingly.

Use the following formula to calculate cylinders for your database:

1. Add the following numbers:
   • The total number of jobs that produce reports
   • The total number of different reports that can be produced
   • The total number of individuals to which reports are distributed (the number of distribution identifiers)
2. Divide the sum of the preceding numbers by 250 and then round the result up to the next integer.
3. If you plan to maintain detailed historical data (set the initialization parameter HDETAIL to YES), do the following:
   • Add the total number of different reports that can be produced to the total number of different bundles that can be produced.
   • Multiply the result by the maximum number of generations of historical data you plan to maintain (the value you specify for the initialization parameter MAXHIST).
   • Divide the product by 195 and round the value up to the next integer (195 is the blocks per cylinder on an IBM 3390 at a block size of 3768).
4. The value you calculate is the number of cylinders to use (do not use fewer than three cylinders).