User Manual

SCSI Commands Reference Manual, Rev. J 57
www.seagate.com General Concepts
SENSE KEY, ADDITONAL SENSE CODE, and ADDITIONAL SENSE CODE QUALIFIER fields
The SENSE KEY, ADDITIONAL SENSE CODE, and ADDITIONAL SENSE CODE QUALIFIER fields are described in 4.5.2.1.
INFORMATION field
The contents of the INFORMATION field is device-type or command specific and is defined within the appropriate standard for the device type
or command of interest. targets shall implement the INFORMATION field. Unless specified otherwise, this field contains:
a) the unsigned LOGICAL BLOCK ADDRESS associated with the sense key, for direct-access devices (device type 0), write-once devices
(device type 4), CD-ROM devices (device type 5), and optical memory devices (device type 7);
b) the difference (residue) of the requested length minus the actual length in either bytes or blocks, as deter-mined by the command, for
sequential-access devices (device type 1), printer devices (device type 2), processor devices (device type 3) and some direct access
device commands, except as defined for d) below. Negative values are indicated by two's complement notation;
c) the difference (residue) of the requested number of blocks minus the actual number of blocks copied or compared for the current
segment descriptor of a COPY, COMPARE, COPY AND VERIFY, or Extended COPY command; or
d) for sequential-access devices operating in buffered modes 1h or 2h that detect an unrecoverable write error when unwritten data
blocks, filemarks, or setmarks remain in the buffer, the value of the information field for all commands shall be:
A) the total number of data blocks, filemarks, and setmarks in the buffer if the device is in fixed block mode (block length field of the
MODE SENSE block descriptor is non-zero and the fixed bit of the WRITE command is one); or
B) the number of bytes in the buffer, including filemarks and setmarks, if the device is in variable mode (the fixed bit of the WRITE
command is 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.
COMMAND-SPECIFIC INFORMATION field
The COMMAND-SPECIFIC INFORMATION field contains information that depends on the command on which the exception condition occurred.
FIELD REPLACEABLE UNIT CODE field
The FIELD REPLACEABLE UNIT CODE field is described in 2.4.1.1.5.
SKSV (Sense-key Specific Valid) bit
1 A sense-key specific valid (SKSV) bit set to one indicates the SENSE KEY SPECIFIC field contains valid information as defined in this man-
ual.
0 An SKSV bit set to zero indicates that the SENSE KEY SPECIFIC field is not as defined by this manual.
SENSE KEY SPECIFIC field
The SENSE KEY SPECIFIC field is described in 2.4.1.1.4.
The additional sense bytes may contain vendor specific data that further defines the nature of the exception condition.
2.4.1.3 Current errors
Response codes 70h and 72h (current error) indicate that the sense data returned is the result of an error or exception condition on
the task that returned the CHECK CONDITION status or a protocol specific failure condition. This includes errors
generated during processing of the command. It also includes errors not related to any command that are detected
during processing of a command (e.g., disk servo-mechanism failure, off-track errors, or power-up test errors).