Persistent Reserve In Parameter Data For Read Reservations - Seagate SCSI Interface Product Manual

SCSI Interface Product Manual, Rev. J
The Generation value allows the application client examining the generation value to verify that the config-
uration of the initiators attached to a logical unit has not been modified by another application client with-
out the knowledge of the examining application client.
[2] The Additional Length field contains a count of the number of bytes in the Reservation Key List. If the Allo-
cation Length specified by the Persistent Reserve In command is not sufficient to contain the entire
parameter list, then only the bytes from 0 to the maximum allowed Allocation Length shall be sent to the
application client. The remaining bytes shall be truncated, although the Additional Length field shall still
contain the actual number of bytes in the Reservation Key List without consideration of any truncation
resulting from an insufficient Allocation Length. This shall not be considered an error.
[3] The Reservation Key List contains all the 8-byte reservation keys registered with the device server
through Persistent Reserve Out Reserve, Preempt, Preempt and Clear, or Register service actions. Each
reservation key may be examined by the application client and correlated with a set of initiators and SCSI
ports by mechanisms outside the scope of this manual.
5.15.2

Persistent Reserve In parameter data for Read Reservations

The format for the parameter data provided in response to a Persistent Reserve In command with the Read
Reservations service action is shown in Table 171.
Table 110: Persistent Reserve In parameter data for Read Reservations
Bit 7
Byte
0 (MSB)
3
4 (MSB)
7
8 (MSB)
n
Notes.
[1] The Generation value is a 32-bit counter in the device server that shall be incremented every time a Per-
sistent Reserve Out command requests a Register, a Clear, a Preempt, or a Preempt and Clear opera-
tion. The counter shall not be incremented by a Persistent Reserve In command, by a Persistent Reserve
Out command that performs a Reserve or Release service action, or by a Persistent Reserve Out com-
mand that is not performed due to an error or reservation conflict. The Generation value shall be set to 0
as part of the power on reset process.
The Generation value allows the application client examining the generation value to verify that the config-
uration of the initiators attached to a logical unit has not been modified by another application client with-
out the knowledge of the examining application client.
[2] The Additional Length field contains a count of the number of bytes in of Reservations Descriptor. If the
Allocation Length specified by the Persistent Reserve In command is not sufficient to contain the entire
parameter list, then only the bytes from 0 to the maximum allowed Allocation Length shall be sent to the
application client. The remaining bytes shall be truncated, although the Additional Length field shall still
contain the actual number of bytes of Reservations Descriptor and shall not be affected by the truncation.
This shall not be considered an error.
[3] The format of a single read Reservations Descriptor is defined in Table 111. There shall be a Reserva-
tions Descriptor for the persistent reservation, if any, present in the logical unit and a Reservations
Descriptor for each element, if any, having a persistent reservation.
6 5
Additional Length (n–7) [2]
Reservations Descriptor [3]
4 3
Generation [1]
2 1
(LSB)
(LSB)
(LSB)
155
0