Request Sense Command ............................................. (03H) - Seagate ST11200 Product Manual

Product Manual - Disc Drive SCSI-2SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
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5.1.1.2 Request Sense Command (03h)
Bit 7
Byte(s)
0 0
1 Logical Unit No
0
2 0
3 0
4
5 0
The Request Sense command (TABLE 5.1.1-3) requests that the disc drive transfer sense data to the initiator
in the format shown in Table 5.1.1-4. The sense data shall be valid for a Check Condition status returned on
the prior command. This sense data shall be preserved by the disc drive for the initiator until retrieval is
requested by the initiator when it sends the Request Sense command or until the receipt of any other com-
mand for the same drive from the initiator that issued the command that resulted in the Check Condition
status. Sense data shall be cleared upon receipt of any subsequent command to the drive from the initiator
receiving the Check Condition status.
If a disc drive sends a Check Condition status as a response to a Request Sense command being in error, it
shall do so only if the error was a fatal error. For example:
1. The disc drive receives a nonzero reserved bit in the command descriptor block.
2. An unrecovered parity error occurs on the Data Bus.
3. A disc drive malfunction prevents return of sense data.
Notes. [1] See "Control Bytes", paragraph 4.2.6.
If any nonfatal error occurs during execution of Request Sense, the disc drive shall return sense data with
Good status. Following a fatal error on a Request Sense command, sense data may be invalid.
The Allocation Length in byte four of the format shown specifies the number of bytes the initiator has allo-
cated for returned sense data. The Allocation Length should always be at least 18 bytes for disc drive devices
for the initiator to receive all of the disc drive sense data. Any other value indicates the maximum number of
bytes that shall be transferred. The disc drive shall terminate the Data In phase when allocation length bytes
have been transferred or when all available sense data have been transferred to the initiator, whichever is
less. The disc drive always returns sense data in the Extended Sense Data Format.
Table 5.1.1-3. Request Sense command
6 5
0 0
0 0
0 0
0 0
Allocation Length in Bytes
0 0
4 3
0 0
0 0
0 0
0 0
0 0
2 1
0 1
0 0
0 0
0 0
0 Flag Link
73
0
1
0
0
0
[1]