C141-E039-01EN
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3.1.15
REQUEST SENSE (03)
Bit
Byte
7
6
5
4
3
2
1
0
0
X‘03’
1
LUN
0
0
0
0
0
2
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
4
Transfer Byte Length
5
0
0
0
0
0
0
Flag
Link
This command transfers sense data to the INIT. This command is executed immediately
without queueing in a system which issues only commands with no tags or links.
The length of the sense data in the IDD is 48 bytes. The "Transfer byte length" field in the
CDB indicates the number of bytes of sense data which can be received by the INIT. The IDD
transfers sense data to the INIT by either of the following two methods, depending on the
specification in the CHANGE DEFINITION command (SCSI level). Furthermore, see item
3.1.4 (SCSI Level) concerning the CHANGE DEFINITION command.
•
If the SCSI-2 mode is specified in the CHANGE DEFINITION command, the IDD
transfers the number of bytes of sense data specified in the "Transfer byte length"
field or the number of bytes in the sense data held by the IDD (48 bytes), whichever is
smaller, to the INIT. When zero is specified in the "Transfer byte length" field, this
command is terminated with nothing transferred, but in this cases also, the sense data
held by the IDD are cleared.
•
If SCSI-1/CCS Mode is specified in the CHANGE DEFINITION command, when
zero is specified in the "Transfer byte length" field, the IDD transfers to the INIT only
4 bytes of sense data, from the top. When a value other than zero is specified in the
"Transfer byte length" field, the IDD transfers to the INIT the number of bytes of
sense data specified in the "Transfer byte length" field or the length of sense data held
by the IDD (48 bytes), whichever is smaller.
As described in 1.6 "Sense Data Hold State," if the IDD terminates a command which it is
currently executing abnormally, it generates sense data for the INIT that issued that command
and maintains those sense data in the hold state.
Sense data are held in a valid state until they are read by a REQUEST SENSE command from
the INIT for which they are held. However, sense data which are being held are cleared by an
ABORT message from the INIT for which they are held, a BUS DEVICE RESET message or
CLEAR QUEUE MESSAGE from any INIT, or a RESET condition.
If a command is terminated with a CHECK CONDITION status, when the SCSI bus enters the BUS
FREE phase unintentionally during execution of a command, or when the INIT detects that there is
no reconnection request from the IDD, the INIT should issue this command and fetch the sense data.