With this attribute, NetBackup retains the snapshot on disk, so that instant recovery can be performed from the snapshot. A normal backup to tape or to other storage is also performed, if you do not select Snapshots only on the Policy Schedules tab.

The Retain snapshots for instant recovery attribute is required for the following specialized types of restore: block-level restore, file promotion, and point-in-time rollback.

These features are described in the NetBackup Snapshot Client Administrator's Guide.