Quantum 10K II - Manual (Page 183)

SCSI Description
5–116 Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives
PERSISTENT RESERVATION IN Command (5Eh) (continued)
The figure and table below illustrate and describe the data fields of Read
Reservations data parameters.
Bit
Byte
7 6 5 4 3 2 1 0
0 - 3
(MSB)
Generation
(LSB)
4 - 7
(MSB)
Additional Length (n – 7)
(LSB)
8 - n
(MSB)
Reservation Descriptors
(See Figure 5-53 / Table 5-55 for detail of a Descriptor Field) (LSB)
Figure 5–52 Read Reservations Parameters — Data Format
Table 5–54 Read Reservations Parameters — Field Descriptions
Data Field Description
Generation The value in this field is a 32-bit counter in the device server that is
incremented each time a PERSISTENT RESERVATION OUT command
requests a Register, Clear, Pre-empt, or Pre-empt and Clear operation. Note
that PERSISTENT RESERVATION IN commands do not increment the counter,
nor do PERSISTENT RESERVATION OUT commands that perform a Reserve or
Release service action, or by a PERSISTENT RESERVATION OUT command
that is not done due to an error or a reservation conflict. The value in the
Generation field is set to 0 as part of the power on or reset processes.
The value in the Generation field allows the application client that examines
the value to verify that the configuration of the initiators attached to a
logical unit has not been modified by another application client without
any notification of the application client doing the examination.
Additional
Length This field contains the count of the number of bytes of Reservation
descriptors (bytes 8 – n). Note that this field contains the number of bytes
regardless of the value prescribed by the Allocation Length field in the
command’s CDB.
Reservations
Descriptors One Reservation descriptor is reported for each unique persistent
reservation on the logical unit when the PERSISTENT RESERVATION IN
command has indicated a Read Reservations action. Figure 5-54 and Table
5-55 detail the contents of each Reservation Descriptors field.