Read Capacity (25) - Fujitsu MAX3073NC - SCSI,80, Dell DC961,Hard Drive Scsi Logical Interface Specifications

3.1.3

READ CAPACITY (25)

Bit
7
Byte
0
1
2
3
4
5
6 0
7 0
8 0
9 0
This command transfers information related to the disk drive's capacity and the data block size to the
INIT.
When bit 0 "PMI (partial medium indicator)" of CDB byte 8 is "0," the logical block address and block
length (byte length) of the final data block which is accessible in the disk drive (user space) are
transferred to the INIT. At this time, the "Logical Block address" field in the CDB must specify zero.
When the "PMI" bit is "1," the logical block address and block length (byte length) of data blocks which
satisfy either of the following conditions is transferred to the INIT.
•
The data block on the track where the specified block exists, which is just before the block where the
first alternate sector processing (not including defective block sector slip processing) is implemented.
However, when alternate sector processing is being implemented in the specified block, the data
block specified in the CDB.
•
When no alternate sector processed data block exists in the track where the specified block exists, the
last data block in that track.
By using this command with the "PMI" bit specified as "1", the INIT can search for usable data space
continuously without being interrupted by data transfers for alternate sector processing or switching of
track.
The format of the data transferred to the INIT by this command is shown in Figure 3.6.
C141-C010
6 5 4
X'25'
LUN 0
Logical Block Address (MSB)
Logical Block Address
Logical Block Address
Logical Block Address (LSB)
0 0 0
0 0 0
0 0 0
0 0 0
3.1 Control/Sense Commands
3 2 1
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0
0
0
0
PMI
Link
3-13