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Fibre Channel Interface Manual, Rev. D 273
12.26 Read Capacity (10) command
The Read Capacity (10) command provides a means for the initiator to request the capacity of the disc drive
information.
Field definitions (listed alphabetically)
Control
See Control Bytes in Section 11.2.1.6.
Logical Block Address
The 32-bit address of the logical block affected by this command.
PMI (Partial Medium Indicator)
0 The information returned in the Read Capacity data is the Logical Block Address and Block Length (in bytes) of the
last logical block of the logical unit. (This value is the same for all drives of the same model number, sector size and
sparing scheme. It is the same regardless of the number of defective blocks the drive has.) The Logical Block
Address in the Command Descriptor Block is set to zero (0) for this option.
1 The information returned is the Logical Block Address and Block Length (in bytes) of the last Logical Block Address
after which a substantial delay (defined as approximately one millisecond for the typical disc drive) in data transfer is
encountered. This returned Logical Block Address is greater than or equal to the Logical Block Address specified in
the Command Descriptor Block. This reported Logical Block Address is the last block prior to a cylinder boundary.
RelAdr (Relative Address)
This function is not supported by drives described in this manual.
Table 178: Read Capacity (10) command (25h)
Bit
Byte
7654321 0
000100101
10000000
RelAdr
Reserved
2
Logical Block Address (MSB)
3
Logical Block Address
4
Logical Block Address
5
Logical Block Address (LSB)
600000000
700000000
80000000PMI
9
Control
25h
Table
number
178
178
178
178