Read Command (08 H ) - Seagate MEDALIST 1080SL Product Manual

Medalist 1080sl SCSI Product Manual, August 1995
3.4.6 Read command (08
When the drive receives the Read command, it transfers data to the
initiator.
The Error Recovery page (01
during a Read command. The Error Recovery page is discussed in
Appendix C.1.
If there is a reservation access conflict, this command terminates with a
reservation conflict status and no data is read. For more information
about the reservation conflict status, see Section 3.2.
In systems that support disconnection, the drive disconnects when a valid
Read command is received, unless the data is available in the cache
buffer and the drive does not need to access the disc. The buffer-full ratio
byte of the Disconnect/Reconnect page determines when the drive
reconnects. (The Disconnect/Reconnect page is discussed in Sec-
tion C.2.) The drive may disconnect, if allowed, whenever there is less
than one block in the buffer.
Because the drive uses read look-ahead and caching functions, it may
read more data into the buffer than specified by the transfer length in the
CDB.
Bytes
7 6
0 0 0
1 LUN
2
3
4
5 0 0
Bytes 1–3 The logical block address specifies the logical block where
the read begins.
Byte 4 The transfer length specifies the number of contiguous
logical blocks of data to be transferred. A transfer length
of 0 indicates that 256 logical blocks are to be transferred.
Any other value indicates the number of logical blocks to be
transferred.
)
H
) determines how the drive handles errors
H
Bits
5 4 3
0 0 1
Logical block address (MSB)
Logical block address
Logical block address (LSB)
Transfer length
0 0 0
39
2 1 0
0 0 0
0 0 0