Calculating the Disk Space Required for the Variable Database

Installation of the IOA Variable Database is preceded by calculation steps that aid in determining the necessary space for the IO access method files.

The IOA Variable Database facility is composed of three IOA Access Method files (each of which requires two additional files, one for the data component and one for the index component, see IOA Variable Database Facility). Each time you add a new database in the List of Databases screen (of Screen IV) you are actually adding a new record to the Database (DBS) file. Each time you add a new column to an existing database in the List of Columns screen (of Screen IV) you are actually adding a new record to the Column (COL) file. Each time you do one of the following actions, you are actually adding a new record to the Variables (VAR) file:

• Directly add a new variable to an existing database in the display screen of Screen IV.
• Indirectly add a new variable to an existing database by executing a WRITEGLOBAL operation, for which a new value for this column/row was not previously defined.

To properly calculate the space required you either need to do one of the following:

• Estimate the average number of databases, columns and rows for the planned databases, and provide this estimate as input to the calculation steps in ICE.
• Rely on values obtained empirically from previous releases or experimentation with the facility.