User Manual

SCSI Commands Reference Manual, Rev. J 47
www.seagate.com General Concepts
2.4.1.1 Descriptor format sense data
2.4.1.1.1 Descriptor format sense data overview
The descriptor format sense data for response codes 72h (current errors) and 73h (deferred errors) is defined in table 12.
RESPONSE CODE field
The contents of the RESPONSE CODE field indicate the error type and format of the sense data (see 2.4.1). For descriptor format sense data, the
RESPONSE CODE field shall be set to 72h or 73h.
SENSE KEY, ADDITIONAL SENSE CODE and ADDITIONAL SENSE CODE QUALIFIER fields
The SENSE KEY, ADDITIONAL SENSE CODE and ADDITIONAL SENSE CODE QUALIFIER fields provide a hierarchy of information. The hierarchy
provides a top-down approach for an application client to determine information relating to the error and exception conditions.
SENSE KEY field
The SENSE KEY field indicates generic information describing an error or exception condition. The sense keys are defined in 2.4.1.5.
ASC (ADDITIONAL SENSE CODE) field
The ADDITIONAL SENSE CODE (ASC) field indicates further information related to the error or exception condition reported in the SENSE KEY
field. Support of the additional sense codes not required by this manual is optional. A list of additional sense codes is in
2.4.1.5. If the device
server does not have further information related to the error or exception condition, the additional sense code shall be set to zero.
ASCQ (ADDITIONAL SENSE CODE QUALIFIER) field
The ADDITIONAL SENSE CODE QUALIFIER (ASCQ) field indicates detailed information related to the additional sense code. If the error or excep-
tion condition is reported by the device server, the value returned shall be as specified in 2.4.1.5. If the device server does not have detailed
information related to the error or exception condition, the additional sense code qualifier shall be set to zero.
ADDITIONAL SENSE LENGTH field
The ADDITIONAL SENSE LENGTH field indicates the number of additional sense bytes that follow. The additional sense length shall be less than
or equal to 244 (i.e., limiting the total length of the sense data to 252 bytes). If the sense data is being returned as parameter data by a REQUEST
SENSE command, then the relationship between the ADDITIONAL SENSE LENGTH field and the CDB ALLOCATION LENGTH field is defined in
2.2.6.
Table 12 Descriptor format sense data
Bit
Byte
7 6 5 4 3 2 1 0
0
Reserved RESPONSE CODE (72h or 73h)
1
Reserved SENSE KEY
2
ADDITIONAL SENSE CODE
3
ADDITIONAL SENSE CODE QUALIFIER
4
Reserved
. . .
6
7
ADDITIONAL SENSE LENGTH (n-7)
Sense Data Descriptor(s)
8
(MSB)
Sense Data Descriptor (first) (see table 13)
. . .
(LSB)
. . .
(MSB)
Sense Data Descriptor (last) (see table 13)
n
(LSB)