About the appliance and the storage shelves
The Veritas 5250 Appliance is a hardware and software storage system that can scale to 429.4TiB of available backup capacity. It consists of a Veritas 5250 Appliance and up to six optional Veritas 2U12 65.5TiB/72TB storage shelves.
The 5250 appliance and storage shelves provide storage capacity in several configurations. You can use the appliance by itself to achieve 9.1TiB to 36.4TiB of usable capacity. You can add storage shelves to any appliance to further increase the storage capacity. The 5250 Appliance supports S Series and D Series storage shelves or a combination of both types of shelves.
You can add up to six Veritas 2U12 65.5TiB/72TB Storage Shelves to an existing 5250 Appliance. Before you place the system into a production environment, you must migrate all MSDP data from the appliance to the first external storage shelf. After you migrate the MSDP data, the amount of usable storage space may fluctuate, depending on how much storage space the MSDP data pool presently uses.
Refer to the Veritas 5250 Appliance Product Description Guide at the following site for details about usable storage options.