Reference Guide

Chapter 4 SCSI Commands
READ BUFFER Command (3Ch)
DLT-S4 Interface Reference Guide 268
Descriptor Mode (03h) 4 In this mode, the drive returns a maximum of 4 bytes of READ BUFFER
descriptor information. The drive returns the descriptor information for
the buffer specified by the Buffer ID. In this mode, the drive does not
reject the invalid Buffer IDs with a
CHECK CONDITION status, but returns
all zeros in the
READ BUFFER descriptor. The Offset Boundary is 3,
indicating that buffer offsets should be integral multiples of 8.
Figure 131 READ BUFFER
Descriptor — Data Format
Read Data from Echo
Buffer (0Ah)
4
In this mode the drive transfers data to the application client from the
Echo Buffer. The Echo Buffer transfers the same data as when the
WRITE
BUFFER
command with the mode field set to Echo Buffer was issued. The
Buffer ID and Buffer Offset fields are ignored in this mode.
The
READ BUFFER command returns the same number of bytes of data as
the drive received in the previous Echo Buffer mode
WRITE BUFFER
command from the same initiator. If a previous Echo Buffer mode
WRITE
BUFFER
command did not complete successfully, the drive terminates
the Echo Buffer mode
READ BUFFER command with a CHECK CONDITION
status, with Sense Key set to
ILLEGAL REQUEST, and the Additional Sense
Code set to
COMMAND SEQUENCE ERROR. If the data in the Echo Buffer
has been overwritten by another initiator, the drive terminates the
command with a
CHECK CONDITION status, with Sense Key set to
ABORTED COMMAND and the Additional Sense Code set to ECHO BUFFER
OVERWRITTEN.
Bit
7 6 5 4 3 2 1 0
Byte
0 Offset Boundary
1 — 3
(MSB)
Buffer Capacity
(LSB)