OEM MANUAL:K6602771
5 SCSI COMMANDS
Revision: 2 / Date: 2002.12.19
Page: 103 / 313
5
SCSI COMMANDS
The SCSI commands are defined as the data structure viewed through the SCSI
interface.
A single command may transfer one or more logical blocks of data.
The controller may disconnect from the SCSI bus while making preparations for data
transfer to make the SCSI bus available to other SCSI devices.
Whenever a command is completed (normally or abnormally), the controller returns the
FCP_RSP Payload to the host computer.
5.1
COMMAND STRUCTURE
A request to the controller is generated by the host computer sending a command
descriptor block (CDB). For some commands, the request is accompanied by a
Parameter List that are transferred in the FCP_DATA Payload to give a detailed
definition of the request.
The CDB consists of the operation code, the logical unit number, the command
parameters and the control byte. Its length varies depending on the value of the
group code in the operation code.
If an invalid parameter is found in the CDB, the controller terminates the command
without accessing the disk medium.
In the rest of this section, only the items that are common to the SCSI commands are
described. Specifications that are unique to the individual commands are found in
Chapter 6.
Table 5-1 shows the format of the standard CDB (for 6-byte commands), Table 5-2
shows that of the standard CDB (for 10-byte commands) and Table 5-3 shows that of
the standard CDB (for 12-byte commands).