Write
Write
The
WRITE
command requests
that
the
Target write
the
data
transferred by
the
Initiator
to
the
media.
The
Target accepts both
the
non-extended (6-byte) and extended (lO-byte)
eDB
formats.
Write
(6-Byte)
Command
DeSCriptor
Block
(COB)
Bit
Byte
7
I
6
I
5
I
4
I
3
I
2
I
1
I
0
00
Opcode =
OAH
01
Logical Unit
Number
I
Logical Block Address (MSB)
02-03
Logical Block Address
(LSB=03)
04
Transfer
Length
05
Control
Byte
Write
(10-Byte)
Command
Descriptor
Block
(COB)
Bit
Byte
7
I
6
I
5
I
4
I
3
I
2
I
1
I
0
00
Opcode = 2AH
01
Logical Unit
Number
I
DPO=O I
FUA
I
Reserved
I
RelAdr
02-05
(MSB=02)
Logical Block Address
(LSB=05)
06
Reserved
07-08
(MSB=07) Transfer Length
(LSB=08)
09
Control
Byte
Logical Block Address. This field specifies
the
logical block
at
which
the
write operation will
begin.
FUA (Forced Unit Access).
If
the
FUA bit is set
to
one (1),
the
WRITE
command will not
return
GOOD Status until
the
logical blocks have actually been written on
the
media.
If
the
FUA bit is set to zero (0), logical blocks may be transferred directly
to
cache memory,
and
GOOD
Status
may be returned
to
the
Initiator prior
to
writing
the
logical blocks to
the
media
if
the
WeE
bit
in Mode page 08H, byte
02
is set. Any error which occurs after
the
GOOD
Status
is returned as a deferred error and information regarding
the
error is not reported until
a subsequent command.
ReIAdr (Relative Address). A one (1) indicates
that
the
logical block address field is a two's
complement displacement. This negative or positive displacement is
to
be added
to
the
logical block address
last
accessed on
the
logical unit
to
form
the
logical block address for this
command. This feature
is
available only when linking commands.
The
feature requires
that
a
previous command in
the
linked group has accessed a block
of
data
on
the
logical unit.
A RelAdr
bit
of zero (0) indicates
that
the
logical block address field specifies
the
first logical
block of
the
range of logical blocks
to
be operated on by this command.
Transfer Length. This field specifies the number
of
contiguous logical blocks
of
data
to
be
transferred. When using the non-extended (6-byte)
eDB
format, a Transfer Length
of
zero
indicates
that
256
logical blocks will be transferred. When using
the
extended (lO-byte)
eDB
DRAFT
SCSI
Command
Descriptions A-57
1/18/93 09:58
To Next Page
Loading...
