When using a NetBackup Storage Lifecycle Policy (SLP) with a Puredisk Storage Unit, you cannot select the "Staged Capacity Managed" retention type. This article explains why that is the case.
Staged Capacity Managed Option
In a nutshell, using the “Capacity Managed” option within a Storage Lifecycle Policy (SLP) with a Puredisk storage unit is not possible. The option is even greyed out when pointing it to a Puredisk storage unit, as shown in the above screenshot.
That kind of made sense to me, but kind of didn’t. So after researching that question through multiple documents and training guides, I finally found the answer in the “Help” button on the above screen (in all places!). It said:
Staged capacity managed is selectable for any disk storage unit that is allowed in a lifecycle. However, for the disk types that support single-instance store (SIS), Staged capacity managed functions to various degrees. In order for Staged capacity managed to operate, NetBackup must know how much space a backup image uses. With SIS enabled on the storage unit, NetBackup cannot know exactly how much space a particular backup image occupies.
The following storage unit configurations use SIS:
PureDisk storage units
NearStore storage units that have either the Enable file system export option enabled or the Enable block sharing option enabled.
Some OpenStorage storage units, depending on the vendor characteristics.
So that’s why we can’t use Capacity Managed SLP’s with a Puredisk based storage unit.