Reassign
Blocks
Defect List Descriptor Format
Bit
Byte
7
I
6
I
5
t
4
J
3
I
2
I
1
I
0
00-03
(MSB=OO)
Defect Logical Block Address
(LSB=03)
The
Defect Descriptor specifies a 4-byte Defect Logical Block Address
that
contains
the
defect.
The
defect descriptors shall
be
in ascending order.
If
the
logical
unit
has insufficient capacity
to
reassign all of
the
logical blocks specified
in
the
defect descriptors,
the
command shall terminate with a CHECK CONDITION
status
and
the
Sense Key will be set
to
MEDIUM ERROR.
The
additional Sense Code will
be
NO
DEFECT
SPARE LOCATION AVAILABLE (32H).
The
logical block address of
the
first logical block
not reassigned shall be returned in
the
Information Bytes-of
the
sense
data.
During a reassign operation, all
data
residing on
the
track with
the
specified defective
block(s), except
that
contained within
the
defective block(s), is moved
to
a new physical track.
If
the
Target is unable
to
recover
data
from any of these block( s) affected by
the
operation
but
not contained in
the
defect descriptor list,
the
command is terminated with
CHECK
CONDITION
status
and
a Sense Key of MEDIUM
ERROR.
The
additional Sense Code will
be set
to
UNRECOVERED READ
ERROR
(llH),
and
the
information bytes will contain
the
logical block address of
the
new defect. These additional defect(s) should
be
added
to
the
reassignment defect list and
the
command reissued.
All blocks affected by the reassignment operation
but
not included in
the
defect descriptor
list, are verified following
the
reassignment.
If
the
verification fails,
the
data
will be reassigned
to
another physical location.
If
this second reassignment operation fails,
the
command is
terminated
with CHECK CONDITION
status,
a Sense Key of MEDIUM ERROR,
and
an
additional sense code of SPARE OPERATION FAILED. In this case,
the
media configuration
remains as
it
was prior
to
the
command.
The
spare
track
on which
the
original verify failed is
marked as bad.
This
allows a reissue of
the
same Reassign Blocks c-ommand
to
step
through
spare tracks if consecutive spare tracks are defective. Multiple failures of this command
probably indicate a hardware failure
..
A-38 SCSI Command Descriptions
DRAFT
1/18/93 09:58
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