Reference Guide

Chapter 4 SCSI Commands
REQUEST SENSE Command (03h)
DLT-S4 Interface Reference Guide 308
Sense Key The Sense Key values are described in table 173.
Information Contains the difference (residue) between the requested length minus the actual
length in bytes, blocks, or Filemarks, as determined by the command. Negative
values are indicated by two’s complement notation. The bytes are valid for all
READ, WRITE, SPACE, and VERIFY commands for which the drive generated a
CHECK CONDITION status.
Additional Sense
Length
Specifies the number of additional sense bytes to follow. If the value in the
Allocation Length field of the CDB is too small to transfer all of the Additional
Sense bytes, the Additional Sense Length is not adjusted to reflect the truncation.
Command
Specific
Information
Command Specific Information bytes can be logged by the operating system on
error conditions. On tape medium errors, such an entry usually contains the current
SCSI logical block address (LBA).
Additional Sense
Code (ASC)
This field and the Additional Sense Code Qualifier field provide additional
information about the Sense Key and the cause of a
CHECK CONDITION status.
Additional Sense Codes are listed in table 174
.
Additional Sense
Code Qualifier
(ASCQ)
This field and the Additional Sense Code field provide additional information
about the Sense Key and the cause of a
CHECK CONDITION status. Additional Sense
Code Qualifiers are discussed in table 174
.
Field Replaceable
Unit Code
Not used. Always set to 0.
SKSV Sense-Key Specific Valid. When set to 1, indicates that the data in the Sense-Key
Specific fields is valid.
C/D Command / Data. When set to 1, indicates that the illegal parameter is contained in
the CDB. When set to 0, indicates that the illegal parameter is in the Parameter List
from the initiator.
BPV Bit Pointer Valid. When set to 1, indicates that the Bit Pointer field is valid and
designates which bit of the byte designated by the field pointer is in error. For a
multi-bit field, it points to the most significant bit of the field.
Bit Pointer When BPV is set to 1, indicates either the most significant bit of the field in error or
the most significant invalid bit within the field. Reserved fields are treated as
individual bit fields— the most significant reserved bit that is set is indicated rather
than the most significant bit of the entire reserved field. When the field in error uses
an entire byte, the Bit Pointer field is typically not used (BPV is set to 0).
Field Description