Interface Implementation
18
Sense Data, Unit Attention and Deferred Errors are maintained for each initiator. Mode
Parameters are common to all initiators.
The untagged queuing model implemented by the drives guarantees that all commands are
executed in strict order of receipt. Certain non-media access type commands, such as
TEST UNIT
READY
,
INQUIRY
,
REQUEST SENSE
and
REPORT LUNS
, are implicitly allowed to queue-jump other
media access type commands, such as
REWIND
.
The parallel SCSI drive supports the full command queuing model with a queue depth of 1
(necessary for connectivity purposes). The FC drive supports the basic queuing model with a
queue depth of 4. See “Standard Inquiry Data format (LUN0)” on page 40 for details of the BQue
and CmdQue bits which define this support.
Fibre Channel operation
NOTE:
This applies only to Fibre Channel drives.
The following sections have information specific to Fibre Channel operation:
•
“Fibre Channel Logical Unit Control mode page” on page 84
•
“Fibre Channel Port Control mode page” on page 85
•
“Vital Product Data pages” on page 44
Fibre Channel addressing
Before describing HP’s implementation of Fibre Channel addressing, the concepts of
Names
and
Addresses
need to be clarified.
Names
Names are 64-bit identifiers assigned permanently to the tape drive during manufacture. They are
commonly referred to as World Wide Names since they must be guaranteed unique. The names
are typically used for identifying the device to operating systems, since addresses are assigned
dynamically. There at least eight different name formats distinguished by the Network Address
Authority (NAA). Only one is used on HP Ultrium drives. This is the IEEE Registered Name
(NNA=5) and has the following format:
This name is made up of three fields:
•
NAA Identifier (4 bits). “5” indicates a IEEE Registered Name.
