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SCSI Description
5-98 Maxtor Atlas 10K III
Table 5-120 provides detailed descriptions of each of the PERSISTENT
RESERVATION OUT command’s seven possible service actions (Service Action
codes appear in bits 0 – 4 of Byte 1).
PERSISTENT RESERVATION OUT Command’s Service Action Descriptions
Type
The value of the Type field specifies the characteristics of the persistent reservation
being established for all data blocks within the extent or within the logical unit. Refer
to Table 5-121 for the applicable Type codes and their meanings
Parameter
List Length
Fields contained in the PERSISTENT RESERVATION OUT parameter list specify the res-
ervation keys and extent information required to perform a persistent reservation ser-
vice action.
The parameter list is 24 bytes in length; the Parameter List Length field contains 24
(18h) bytes.
00h Register
When the command executes a Register service action, it registers a reserva-
tion key with a device server without generating a reservation. The device serv-
er holds these reservation keys from each initiator that performs a PERSISTENT
RESERVATION OUT command with a Register service action until the key is
changed by a new PERSISTENT RESERVATION OUT command with Register
service action from the same initiator, or until the initiator registration is re-
moved by:
• Powering down the logical unit, if the last
Activate Persist Through Power Loss
(APTPL; see Figure 5-55 and Table 5-61)
received by the device server was 0;
• Performing a Clear service action;
• Performing a Pre-empt service action;
• Performing a Pre-empt and Clear service
action; or
• Performing a Register service action from the
same initiator with the value of the service
action reservation key set to 0.
When a reservation key has not yet been established or when the reservation
key has been removed, a reservation key of 0 is used when the initiator per-
forms a PERSISTENT RESERVATION OUT with the Register service action.
When the reservation has been removed, no information is reported for the ini-
tiator in the Read Keys service action of the resulting PERSISTENT RESERVA-
TION IN command.
01h Reserve
A PERSISTENT RESERVATION OUT command with Reserve service action cre-
ates a persistent reservation with a specified Scope and Type.
Persistent reservations are not superseded by a new persistent reservation from
any initiator except by the execution of a PERSISTENT RESERVATION OUT
command that specifies either a Pre-empt or Pre-empt and Clear service action.
New persistent reservations that do not conflict with an existing persistent res-
ervation execute normally. Persistent reservations of logical units or extents
having the same Type value are permitted if no conflicting persistent reserva-
tions are held by another initiator. When these types of overlapping reserva-
tions are released, each of the extent reservations and logical unit reservations
are removed with a separate Release service action. Multiple identical reserva-
tions from the same initiator are all released simultaneously via a single Release
service action that matches the reservations.