Persistent Reserve In Parameter Data For Read Reservations - Seagate Ultra160 Product Manual

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[2] The ADDITIONAL LENGTH field contains a count of the number of bytes in the Reservation Key List. 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 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 initia-
tors and SCSI ports by mechanisms outside the scope of this manual.
8.15.2

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 173.
Table 173: PERSISTENT RESERVE IN parameter data for Read Reservations
Bit 7
Byte
0 (MSB)
3
4 (MSB)
7
8 (MSB)
n
[1] The GENERATION value is a 32-bit counter in the device server that shall be incremented every time a
PERSISTENT RESERVE OUT command requests a Register, a Clear, a Preempt, or a Preempt and
Clear operation. 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 command 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
configuration of the initiators attached to a logical unit has not been modified by another application client
without 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 174. There shall be a
RESERVATIONS 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
GENERATION [1]
ADDITIONAL LENGTH (n–7) [2]
RESERVATIONS DESCRIPTOR [3]
SCSI Interface Product Manual, Rev. B
4 3 2 1
(LSB)
(LSB)
(LSB)
0