Tandberg Data SLR AUTOLOADER PROGRAMMER, Руководство пользователя, Страница: 53 / 62

Tandberg Data SCSI Commands
______________________________________________________________________
Tandberg SLR Autoloader SCSI Functional Specifications 2-47
2.14 RESERVE 16h
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (16h)
1 Logical Unit Number 3rdPty Third Party Device ID Element
2 Reservation Identification
3 Element List Length (MSB)
4 Element List Length (LSB)
5 Vendor Unique Reserved Flag Link
The RESERVE command reserves the library or elements for exclusive use by the
requesting initiator. The reservation remains in effect until one of the following
conditions is met:
•
The initiator that made the reservation sends another RESERVE command.
•
The device is released by RELEASE from the same initiator.
•
A BUS DEVICE RESET message is received from any initiator.
•
A hard reset occurs.
The occurrence of the last two conditions is indicated by the device returning a CHECK
CONDITION status with a sense key of UNIT ATTENTION on the next command
following the condition. It is not an error to issue RESERVE to a device that is currently
reserved to the requesting initiator.
If the logical unit has previously been reserved by another initiator, the target returns a
RESERVATION CONFLICT status.
If, after honoring the reservation, any other initiator attempts to perform
any command except INQUIRY, REQUEST SENSE, or RELEASE, the
command is rejected with a RESERVATION CONFLICT status. A
RELEASE command issued by another initiator is ignored by that reserved
logical unit.
3rdPty
The third-party reservation option for RESERVE UNIT allows an initiator
to reserve a logical unit for another SCSI device. If the third-party (3rdPty)
bit is zero, then the third-party reservation option is not requested. Since
the device does not support third party reservation, this bit must be set to
zero.
Third Party Device ID
The Third Party Device ID field contains the SCSI ID of the third party
device if the 3rdPty bit is set to one. Since the device does not support third
party reservation, this field should be set to zero.
Element
If the element bit is zero, the entire unit is reserved for the requesting
initiator. If the element bit is one, a series of elements is reserved, as
identified by the reservation identification field and specified by the element
list descriptor.