Seagate Fibre Channel Interface - Manual (Page 265)

Fibre Channel Interface Manual, Rev. D 251
12.16.2 Persistent Reserve In parameter data for read reservation
The format for the parameter data provided in response to a Persistent Reserve In command with the Read
Reservation service action is shown in Table 164.
Field definitions (listed alphabetically)
Additional Length
This field contains the number of bytes to follow in Reservation descriptors. If the allocation length specified by the Persis-
tent Reserve In command is not sufficient to contain the entire parameter list, only the bytes from 0 to the maximum allowed
allocation length are sent to the application client. The remaining incremental bytes are truncated; however, the Additional
Length field will still contain the actual number of Reservation Descriptor bytes and will not be affected by the truncation
(this is not considered an error).
Generation
The Generation value is as defined for the Persistent Reserve In Read Keys parameter data. See Section 12.16.1, “Persis-
tent Reserve In parameter data for read keys.”
Reservation Descriptors
There is one read reservation descriptor for each persistent reservation, if any, present in the logical unit and a Reservation
Descriptor for each element, if any, having a persistent reservation. If a persistent reservation is present in the logical unit
that does not contain elements, there will be a single reservation descriptor in the list of parameter data returned by the
device server in response to the Persistent Reserve In command with a Read Reservation service action. The Reservation
descriptor for each reservation will contain the Reservation Key under which the persistent reservation is held. The Type
and Scope of each persistent reservation as present in the Persistent Reserve out command that created the persistent
reservation is returned.
If a persistent reservation is present in a logical unit that does contain elements, there will be a Reservation descriptor in
the list of parameter data returned by the device server. This is in response to the Persistent Reserve In command with a
Read Reservation service action for the logical unit persistent reservation that is held, if any, and each element persistent
reservation that may be held. The Reservation descriptor contains the Reservation Key under which the persistent reserva-
tion is held. The Type and Scope of the persistent reservation as present in the Persistent Reserve out command that cre-
ated the persistent reservation is returned.
If the Scope is an Element reservation, the Scope-specific Address field contains the element address, zero filled in the
most significant bytes to fit the field. If the Scope is a Logical Unit reservation, the Scope-specific Address field is set to
zero. The obsolete field (bytes 14 and 15) were defined in a previous standard and no longer used. The format of a single
read reservation descriptor is provided in Table 165.
Table 164: Persistent Reserve In parameter data for read reservation
Bit
Byte
7 6 5 4 3 2 1 0
0 (MSB)
Generation :
3 (LSB)
4 (MSB)
Additional Length (n - 7)
:
7 (LSB)
8 (MSB)
Reservation Descriptors (see Table 165) :
n (LSB)
Table
number
164
164
164