Reference Guide

Chapter 4 SCSI Commands
PERSISTENT RESERVE IN Command (5Eh)
DLT-S4 Interface Reference Guide 212
Table 115 Read Keys
Parameters
— Field
Descriptions
READ RESERVATION
Service Action
4
Figure 110 and table 116 illustrate and describe the data fields of Read
Reservation data parameters.
Figure 110 PERSISTENT
RESERVE IN Read
Field Description
PRGeneration Persistent Reservations Generation. The value in this field is a 32-bit counter in
the drive that is incremented each time a
PERSISTENT RESERVE OUT command
requests a Register, Clear, Preempt, Preempt & Abort, or Register & Move
operation. Note that
PERSISTENT RESERVE IN commands do not increment the
counter, nor do P
ERSISTENT RESERVE OUT commands that perform a Reserve or
Release service action or that are not performed due to an error or a reservation
conflict. The value in the Generation field is set to 0 as part of the power-on self
test process.
The value in the Generation field allows the application client that examines the
value to verify that another application client has not modified the configuration
of the initiators attached to a logical unit without notifying the application client
doing the examination.
Additional Length Contains the count of the number of bytes that are in the Reservation Key list
(bytes 8 – n). Note that this field contains the number of bytes in the reservation
key list regardless of the value prescribed by the Allocation Length field in the
command’s CDB.
Reservation Keys All of the Reservation Keys appear as items in a list as bytes 8 through n. Each
entry reflects an 8-byte reservation key registered with the drive using the
PERSISTENT RESERVE OUT Register or Register and Ignore Existing Key service
actions. The application client can examine each key for correlation with a set of
initiators and SCSI ports.