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4.3 Format Commands
C141-C013 241
c. Defect list format
This field indicates the description format of the defect descriptor list that is
actually transferred to the INIT. It is possible for the HDD to transfer defect data
in 3 different formats which it can specify in the CDB, and the values in this field
are the same as the values specified in the "Defect List Format" field in the CDB.
d. Defect list length
This field follows the 4-byte header and indicates the total number of bytes of
defect descriptor list that can be transferred. It has either 4 or 8 bytes,
depending on the format of the defect descriptor. Also, the values shown in
this field are the total number of bytes described in the "Defect List Format"
which specifies the specified type (P List or G List) of defect data, regardless
of the value specified in the "Transfer byte length" field in the CDB. The
INIT should check whether the value shown in this field plus 4 is a smaller
value than that specified in the "Transfer byte count" field in the CDB in
order to confirm that all the defect data requested in this command have been
transferred. Also, since the value shown in this field is divided by the
number of bytes (4 or 8) per defect descriptor (quotient), the INIT can know
the number of defects on the disk media.
(2) Defect descriptor list
The data transferred after the 4-byte header is the "Defect descriptor" list (Defect
data) in which the defect position information are described with the type and
format specified in the CDB. One "Defect descriptor" has a length of 4 bytes
when in the "Block address format," and a length of 8 bytes when in the "Byte
distance from the index format" and "Physical sector address format." The
"Defect descriptors" do not necessarily transfer defect position information in
ascending order.
See the description of the FORMAT UNIT command (Section 4.3.1) concerning
the configuration and contents of the "Defect descriptor" in each format.
1. When "1" is specified in both the "P List" bit and the "G List" bit in the CDB,
and transfer of both the P List and G List is requested, the HDD first of all
transfers the P List, then transfers the G List afterward (merging of the defect
information in the two lists is not performed).
2. When "0" is specified in both the "PList" bit and the "GList" bit in the CDB,
only the header is transferred by that command, but the following information
is shown in the header at this time.
− PList bit: "0"
− GList bit: "0"
− Defect List Length field: The total number of bytes described in the
"Defect List Format" specifying defect data
included in the P List and G List.