SCSI Description
5-96 Maxtor Atlas 10K III
The PERSISTENT RESERVATION OUT comm and is a 10-byte command used
to reserve a logical unit or an extent within a logical unit for the exclusive or shared
use by an initiator. The command is used in conjunction with the PERSISTENT
RESERVATION IN command; it is not used with the RESERVE and RELEASE
commands.
Persis t ent r eser va t i ons c onflict with reservat ions ma de via t he RESERVE command.
Initiat ors th at perform PE RSISTENT RESERVATION OUT act ions are identifie d
by a rese rvat ion ke y assigned by the applica t ion cli ent . The client may use the
PERSISTENT R ES ERV ATIO N IN com mand to identify which other initiators
within a system hold conflicting or invalid persistent reservations and use the
PERSISTENT RESERVATION OUT command to preempt those reservations if
necessary.
Note th at s ince pe rs is te n t res erv atio ns are n o t res e t b y t he T A RG E T RESET tas k
management function or other global actio ns, they can be used to enact device shar ing
among multiple initiators. The PERSISTENT RESERVATION OU T and
PERSI ST E N T R E SERVAT ION IN com mands prov id e th e m e an s for reso lv i ng
contentions in multiple-initiator sy stems with multiple por t target. By using the
reservation key to identify persistent reservations, it is possible to determine which
ports hold conflicting persistent reservations and to take over such reservations from
failing or “greedy” initiators.
illustrates the format of the PERSISTENT RESERVATION OUT command. Table
5-119 explains the data fields of the command.
PERSISTENT RESERVATION OUT Command Descriptor Block-Da ta Format
0 Ope ration C o de (5Fh )
1 Reserved Service Action
2 Scope Type
3 - 6 Re served
7 – 8 (MSB)
Parameter List Length (18h)
(LSB)
9 Control