5-100 Maxtor Atlas 10K V
5.23 READ DEFECT DATA Command (12) (B7h)
The READ DEFECT DATA (12) command directs the drive to report defect
information about the drive’s medium. Refer to the FORMAT UNIT command for
information about defects. The data sent to the host in the command’s data-in buffer
transfer consists of a four-byte Defect List header (Table 5-138 and Table 5-139),
followed by any Defect Descriptors (Table 5-136 and Table 5-137).
The READ DEFECT DATA (12) Command Descriptor Block is shown in Table 5-
134; the data fields are described in Table 5-135.
Table 5-134 READ DEFECT DATA (12) Command-Data Format
Table 5-135 READ DEFECT DATA (12) Command-Field Description
1
All in-line spared blocks do not have an associated LBA, and, therefore, will not be seen in Logical Block Format.
Bit
Byte
76543210
0 Operation Code (B7h)
1 Reserved Plist Glist Defect List Format
2 - 5 Reserved
6 - 9
(MSB)
Allocation Length
(LSB)
10 Reserved
11 Control
Field Description
PList
When the value is 0, the returned data does not include the Primary Defect List.
When the value is 1, the returned data includes the Primary Defect List. The defects are returned
in ascending order.
GList
When the value is 0, the returned data does not include the Grown Defect List.
When the value is 1, the returned data includes the Grown Defect List. The defects are returned in
order of occurrence.
When both PList and GList are set to 1, the Primary Defect List and the Grown Defect List are
returned. The Plist is returned followed by the Glist (the lists are not merged). When both are set
to 0, only the Defect List Header (Table 5-138) is reported to the initiator.
Defect List
Format
This field specifies the format in which the defect descriptors are to be returned. The supported
formats are:
000b
Block Format (Table 5-136).
1
100b Bytes from the Index (Table 5-137). The data returned from this mode
does not include defects outside normal user space.
101b Physical Sector Format (Table 5-137). Default format. The defects re-
turned from this mode do not include defects outside normal user space.
Allocation
Length
If the number of defect descriptors the SCSI device has assigned does not exceed the capability of
the ALLOCATION LENGTH field size but contains a value that is insufficient to transfer all of
the defect descriptors, the defect list length shall not be adjusted to reflect the truncation and the
device server shall not create a CHECK CONDITION status. The initiator is responsible for
comparing the defect list length and the allocation length to determine that a partial list was
received. If the number of defect descriptors the SCSI device has assigned exceeds the capability
of the ALLOCATION LENGTH field size, the drive shall transfer no data and return a CHECK
CONDITION status and the sense key shall be set to ILLEGAL REQUEST and the additional
sense code set to INVALID FIELD IN CDB.
