Dell PowerVault TL4000 SCSI Reference Guide - Page 96

reservation

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RESERVE 10 (56h) The RESERVE and RELEASE commands provide the mechanism for contention resolution in multiple initiator systems. The third-party reservation allows logical units to be reserved for another specified SCSI device. When a initiator reserves the library, only INQUIRY, LOG SENSE, RELEASE, REQUEST SENSE, REPORT LUNS, READ ELEMENT STATUS with CurData set and ALLOW MEDIUM REMOVAL commands are accepted from other initiators. All other commands result in a Reservation Conflict status. Bit 7 Byte 0 1 2 3 4 5 6 7 (MSB) 8 9 6 LUN 5 4 3 2 Operation Code (56h) 3rdPty Reserved Obsolete Third-Party Device ID Reserved Reserved Reserved Parameter List Length Control 1 0 LongID Reserved (LSB) Field descriptions: LongID: Device IDs greater than 255 are not supported, therefore setting of LongID will result in a Check Condition status. The Sense Key will be set to ILLEGAL REQUEST and the sense data to INVALID FIELD IN CDB. 3rdPty: If the third party (3rdPty) bit is zero, then a third-party reservation is not requested. If the 3rdPty bit is zero then the LongID and Parameter List Length field shall be ignored. If the 3rdPty bit is one then the library is reserved by the initiator ID specified in the Third-Party Device ID field. The reservation is preserved until it is superseded by another valid RESERVE command from the initiator that made the reservation or until it is released by the same initiator, by a SCSI RESET message, or by a Hard Reset condition, or by a power-on cycle. The library shall ignore any attempt to release the reservation made by any other initiator. Third-Party Device ID: This field provides the Device ID for the third party when 3rdPty bit is set. 3-82 TL2000 and TL4000 SCSI Reference

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RESERVE
10
(56h)
The
RESERVE
and
RELEASE
commands
provide
the
mechanism
for
contention
resolution
in
multiple
initiator
systems.
The
third-party
reservation
allows
logical
units
to
be
reserved
for
another
specified
SCSI
device.
When
a
initiator
reserves
the
library,
only
INQUIRY,
LOG
SENSE,
RELEASE,
REQUEST
SENSE,
REPORT
LUNS,
READ
ELEMENT
STATUS
with
CurData
set
and
ALLOW
MEDIUM
REMOVAL
commands
are
accepted
from
other
initiators.
All
other
commands
result
in
a
Reservation
Conflict
status.
Bit
7
6
5
4
3
2
1
0
Byte
0
Operation
Code
(56h)
1
LUN
3rdPty
Reserved
LongID
Reserved
2
Obsolete
3
Third-Party
Device
ID
4
Reserved
5
Reserved
6
Reserved
7
(MSB)
Parameter
List
Length
8
(LSB)
9
Control
Field
descriptions:
LongID:
Device
IDs
greater
than
255
are
not
supported,
therefore
setting
of
LongID
will
result
in
a
Check
Condition
status.
The
Sense
Key
will
be
set
to
ILLEGAL
REQUEST
and
the
sense
data
to
INVALID
FIELD
IN
CDB.
3rdPty:
If
the
third
party
(3rdPty)
bit
is
zero,
then
a
third-party
reservation
is
not
requested.
If
the
3rdPty
bit
is
zero
then
the
LongID
and
Parameter
List
Length
field
shall
be
ignored.
If
the
3rdPty
bit
is
one
then
the
library
is
reserved
by
the
initiator
ID
specified
in
the
Third-Party
Device
ID
field.
The
reservation
is
preserved
until
it
is
superseded
by
another
valid
RESERVE
command
from
the
initiator
that
made
the
reservation
or
until
it
is
released
by
the
same
initiator,
by
a
SCSI
RESET
message,
or
by
a
Hard
Reset
condition,
or
by
a
power-on
cycle.
The
library
shall
ignore
any
attempt
to
release
the
reservation
made
by
any
other
initiator.
Third-Party
Device
ID:
This
field
provides
the
Device
ID
for
the
third
party
when
3rdPty
bit
is
set.
3-82
TL2000
and
TL4000
SCSI
Reference