Example of a BCDS calculation

This example uses the work sheet in Figure 1 and several assumptions about the environment to calculate how many cylinders are needed for the BCDS.

Assuming that your environment consists of the following:
5 average number of backup versions (active and retained) of any data set (bver)
150␠000 data sets that you want automatically backed up (nds)
calculate the space for your current BCDS records, using this formula:
```
   398  x  bver  x  nds   =  subtotal
```
Substituting the values for bver and nds results in:
```
   398  x  5  x  150␠000   =  298␠500␠000
```
Multiply the subtotal by 1.5 to allow for additional BCDS growth.
```
   298␠500␠000 x  1.5  =  447␠750␠000
```
Divide the total number of bytes per cylinder (using 3390 as an example) into the total number of bytes required by the BCDS. If the result is a fraction, round up to the next whole number. This is the number of cylinders you should allocate for the BCDS.
Total bytes used by the BCDS 447␠750␠000
___________________ = ________________ = 607.23 or approximately 607 cylinders
Total bytes per cylinder (3390)

737␠280