9.7.1.2 Calculating the Virtual Size for Grid Disks

You can use the following formula to get a rough estimate of the virtual size to assign for a sparse ASM disk group:

Virtual size required for sparse disks =
   (SUM(full virtual size of all Exadata snapshots) + Physical space allocated)
   * ASM Redundancy

To continue with the example from the previous section, you have 10 Exadata snapshots. If they were full copies of the test master, they would be 250 GB each.

The following shows the calculation for the total virtual space:

Full size for 5 snapshots per test master, for a total of 10 snapshots:
    10 * 250 GB =                                                      2500 GB
Size of the 2 test masters: 2 * 250 GB =                                500 GB
Subtotal                                                               3000 GB
Normal redundancy: 2 * 3000 GB =                                       6000 GB

Divide this value by the number of disks to determine the virtualsize parameter for each disk. The virtual size for each grid disk should be allocated on 16 MB boundaries. If the virtualSize parameter in MB for each grid disk is not evenly divisible by 16, adjust up to a 16 MB boundary.

Note that you should set aside additional space to use for multiple projects and through multiple iterations.