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03 through 04) are ignored.
If the unit or any extent within the
unit is previously reserved, then the unit shall respond by a
RESERVATION CONFLICT Status.
If any other Initiator then subsequently attempts to perform a
READ or WRITE operation on the reserved unit,
that command shall
be rejected with RESERVATION CONFLICT Status.
If a
REQUEST
SENSE command is executed,
a No Sense error code will be
presented.
The Reservation Identification (Byte 02) provides a means for an
Initiator to identify each Extent Reservation.
This allows an
Initiator
in
a
multi-tasking
environment
to have multiple
reservations outstanding.
The Reservation Identification is used
in the RELEASE command to specify which reservation is to be
released.
Extent Reservation Within Units:
Extents within a unit may be reserved,
each with a separate
Reservation Type by setting the Extent bit to 1.
If the
reservation
cannot
be
granted
because
of
conflicts
with
a
previous reservation, a RESERVATION CONFLICT status indication is
posted ..
Reservations are only active when all extents are free
from conflict with currently active reservations.
If the extent bit is one, then:
(1)
The Extent List is checked for number of extents in the
reservation request.
The ACB-5500 supports only one extent.
I f the Extent Li st conta i ns more than one extent, then the
command shall be rejected with CHECK CONDITION Status and an
ILLEGAL BLOCK REQUEST (2l H ) error.
(2)
The Extent List will
be checked for valid extent block
addresses.
If any address is invalid for this unit, then
the command is rejected with the CHECK CONDITION Status and
a Sense Key of ILLEGAL BLOCK REQUEST (2l H ).
(3)
If there already is an active unit reservation for the unit,
the command shall be rejected with CHECK CONDITION Status
and a Sense Key of ILLEGAL REQUEST.
(4)
If the requested reservation does not conflict with any
active reservation, then the extent specified is reserved
until release by a RELEASE command from this Initiator or by
a BUS DEVICE RESET message from any Initiator or a "Hard"
RESET condi tion.
500504-00
6-37
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