SCSI-3 PGR supports multiple nodes accessing a device while at the same time blocking access to other nodes. SCSI-3 PGR supports multiple paths from a host to a disk and SCSI-3 PGR reservations are persistent across SCSI bus resets.

By contrast, SCSI-2 reservations support only one host, with one path. This means if there is a need to block access for data integrity concerns, only one host, and one path remain active. This limits access to the device to only one path and prevents the use of multiple paths even if they are available.

SCSI-3 PGR uses a concept of registration and reservation. Systems accessing a device register a key with a SCSI-3 device. Each system registers its own key. Multiple systems registering keys form a membership. Registered systems can then establish a reservation. The reservation type is set to "Exclusive Access - Registrants Only". This means that only some commands are allowed and there is only one persistent reservation holder. With SCSI-3 PGR technology, blocking write access can be done by removing a registration from a device.

In the Storage Foundation implementation, a node registers the same key for all paths to the device.

For DMP DSMs, the Active/Active setting is implemented by translating SCSI reserve or release commands to SCSI-3 PGR commands.