Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
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The fundamental unit of transfer on a Fibre Channel link is the 8b/10b encoded Transmission Character. Only 256 characters
are required to represent a byte of data so the set of valid transmission characters is sub-divided into Data Characters and Spe-
cial Characters.
A Word is a group of four consecutive transmission characters.
An Ordered Set is a word that starts with a special character (to give word and byte sync) and which has special significance to
the communication protocol. Fibre Channel defines the following types of ordered sets:
• Frame delimiters
• Primitive signals
• Primitive sequences
A Frame Delimiter immediately precedes or follows the contents of a frame (see 17.1.4, “Frames” on page 56). Fibre Channel
defines the following:
•SOF Start of frame
•EOF End of frame
A Primitive Signal is an ordered set that has special meaning when received by itself. Fibre Channel defines the following:
• R_RDY Receiver Ready
• IDLE Idle
FC-AL adds the following:
• ARBx Arbitrate
• ARB(F0) Arbitrate
•OPNyx Open Full-duplex
•OPNyy Open Half-duplex
•OPNfr Open Broadcast Replicate1
•OPNyr Open Selective Replicate1
•CLS Close
•MRKtx Mark1
A Primitive Sequence is an ordered set that is transmitted repeatedly and continuously. Three or more of the ordered sets must
be received consecutively in order to recognize the primitive sequence. Fibre Channel defines the following:
•NOS Not Operational2
•OLS Offline2
•LR Link Reset2
• LRR Link Reset Received2
FC-AL adds the following:
•LPByx Loop Port Bypass
• LPEyx Loop Port Enable
1. Since normal buffer-to-buffer flow control is disabled when OPNr is used, there is no guarantee that the drive has a buffer available to receive an
in-bound frame. It is therefore, recommended that OPNr not be used.
2. Used to convey information about a dedicated connection and therefore not relevant to FC-AL. If detected during an open connection, the drive
will immediately close. Otherwise it will simply re-transmit.