Hitachi HUS154530VLF400 User Manual
Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
103
18.0 SCSI-FCP
This section describes the drive’s implementation of SCSI-FCP. SCSI-FCP is the FC-4 mapping recommended by the Disk
Profile. It maps the ANSI SCSI protocol onto the FC-PH functions.
Profile. It maps the ANSI SCSI protocol onto the FC-PH functions.
Note: PLDA 2.1 specifies: “Reserved FC-PH fields are not required to be checked for zeroes. Validity bits set to 0 remove any
requirement to check the corresponding field for zeroes (e.g., if F_CTL bit 3=0, receiving N_Ports are not required to verify
that the parameter field in word 5 of the frame header contains zeroes).” As such, the drive does not validate 1) reserved FC
fields or 2) fields that are not reserved but are not valid for the current frame (as the example above with F_CTL bit 3). This
does not apply to any reserved field checking and testing within the FCP_CDB. These fields are checked as per ANSI SCSI
requirements.
requirement to check the corresponding field for zeroes (e.g., if F_CTL bit 3=0, receiving N_Ports are not required to verify
that the parameter field in word 5 of the frame header contains zeroes).” As such, the drive does not validate 1) reserved FC
fields or 2) fields that are not reserved but are not valid for the current frame (as the example above with F_CTL bit 3). This
does not apply to any reserved field checking and testing within the FCP_CDB. These fields are checked as per ANSI SCSI
requirements.
18.1 Terminology
The SCSI Architecture Model (SAM) defines a new SCSI vocabulary in order to remain independent from physical protocol
and interconnect. Common SCSI-2 terms have been replaced and new ones introduced.
and interconnect. Common SCSI-2 terms have been replaced and new ones introduced.
As might be expected, the terminology used to describe SCSI-FCP is a problem. It needs elements of SAM and Fibre Channel.
Most of the Fibre Channel terms have been introduced in 1.0, “FC-AL Attachment”, and some essential SAM terms are cov-
ered here. However, SAM is still recommended reading!
Most of the Fibre Channel terms have been introduced in 1.0, “FC-AL Attachment”, and some essential SAM terms are cov-
ered here. However, SAM is still recommended reading!
SCSI-FCP describes all communication in terms of Fibre Channel Information Units (IUs). FC-PH defines these simply as
"sequences that have special meaning to the FC-4" (i.e. SCSI-FCP).
"sequences that have special meaning to the FC-4" (i.e. SCSI-FCP).
IUs are used to send commands, data, and status; bus phases are part of parallel SCSI and no longer exist. Execution of a com-
mand requires several IUs to pass between theTarget and Initiator so an I/O Process (IOP) equates to a Fibre Channel
exchange. In fact, the exchange ID is used as the command tag.
mand requires several IUs to pass between theTarget and Initiator so an I/O Process (IOP) equates to a Fibre Channel
exchange. In fact, the exchange ID is used as the command tag.
An IOP is represented in the Target by a Task. The Initiator uses Task Management functions to control execution of the task
in the Target. IUs are used to transfer Task Management functions.
in the Target. IUs are used to transfer Task Management functions.
SAM defines a Target as consisting of a Task Manager and one or more Logical Units. The Task Manager handles all the Task
Management functions and the logical unit handles commands.
Management functions and the logical unit handles commands.
The logical unit consists of a Target and a Task Set. The Target actually executes the commands and the task set is simply what
used to be known as the Command Queue.
used to be known as the Command Queue.
SCSI-FCP recognizes that Targets and Initiators may simply be software procedures and therefore calls them Processes.