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280 Fibre Channel Interface Manual, Rev. D
12.29 Read Defect Data (12) command
The Read Defect Data (12) command requests that the target transfer the medium defect data to the initiator. If
the logical unit is reserved, a reservation conflict occurs when a Read Defect Data (12) command is received
from an initiator other than the one holding a logical unit reservation. This command is rejected with Reserva-
tion Conflict status if the reservation conflict is due to a logical unit reservation. Read Defect Data (12) com-
mands with a reservation conflict are terminated with Reservation Conflict status. The Read Defect Data (12)
command is not evaluated for extent reservation conflicts. For example, extent reservations do not conflict with
the Read Defect Data (12) command.
This command is implemented with the disc drive specific parameters listed in Table 184.
Field definitions (listed alphabetically)
Allocation Length
The number of bytes the initiator has allocated for the returned defect data. An Allocation Length of zero indicates that no
Read Defect Data is transferred. Any other value indicates the maximum number of bytes to be transferred. The disc drive
terminates the Data In phase when the Allocation Length bytes have been transferred or when all available defect data has
been transferred to the initiator, whichever is less.
Control
See Section 11.2.1.6.
Defect List Format
Bits 2, 1, 0 in the CDB should be 1 0 0, respectively, to signify a defect list in the Bytes from Index format, or 1 0 1, respec-
tively, to signify a defect list in the Physical Sector format. If neither of these two, the disc drive responds with the defect list
in the drive’s default format (physical sector) and creates the Check Condition status with Recovered Error sense key (1h)
and additional sense error code (1C) at the end of the Read Defect Data transfer.
P List and G List bits
The disc drive interprets the P and G bits as follows:
Bit P Bit G Interpretation
0 0 Return Defect List header only. Target returns only the defect list header.
0 1 Return the growth “G” list only. This list reflects the grown or “G” list as defined in Section 12.5.
Table 184: Read Defect Data (12) command (B7h)
Bit
Byte
76543210
010110111
1 Reserved P List G List Defect List Format
2
Reserved
3
Reserved
4
Reserved
5
Reserved
6MSB
Allocation Length
7
8
9 LSB
10
Reserved
11
Control
B7h
Table
number
184
184
184
184