HP 330834-B21 - StorageWorks Ultrium 460 Tape Library Drive Module, Техническое справочное руководство

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40 Glossary
In synchronous data transfer, the initiator and target work in synchronization,
allowing transmission of a packet of data to start before acknowledgment of
the previous transmission.
In
wide (16-bit) data transfer, two bytes are transferred at the same time
instead of a single byte.
HP Ultrium drives support asynchronous, synchronous and narrow (8-bit)
wide transfers.
fibre channel Fibre Channel provides an inexpensive yet expendable means of quickly
transferring data between workstations, mainframes, supercomputers,
desktop computers, storage devices, displays and other peripherials.
Although it is called Fibre Channel, its architecture represents neither a
channel nor a real network topology. It allows for an active intelligent
interconnection scheme, called a fabric, to connect devices. All a Fibre
Channel port has to do is to manage a simple point-to-point connection
between itself and the fabric. The most prominent Fibre Channel standard is
Fibre Channel Arbitrated Loop (FC-AL).
Several common ULPs (Upper Level Protocols) including IP and SCSI can run
on Fibre Channel, merging high-speed I/O (up to 2 Gb/s) and network
functionality in a single connectivity technology.
filemark A mark written by the host to the tape that can be searched for, often using
the drive’s fast-search capability. It does not necessarily separate files. It is up
to the host to assign a meaning to the mark.
immediate mode
A mode of responding to SCSI commands where the drive or other peripheral
does not wait until the command has finished before returning status
information back to the host. For writing filemarks, Immediate mode can
significantly improve the performance of systems that do not set the
Immediate bit when sending a SCSI
WRITE FILEMARKS
command. On the
other hand, data is not flushed to tape in response to a filemark command.
infinite flush By default, the buffer in the drive is flushed every 5 seconds. Infinite flush
avoids frequent starting and stopping of the mechanism when using a very
slow application. It also avoids losing capacity through the flushing of partly
written groups. On the other hand, infinite flush means that data can remain
in the buffer for very long periods of time, and could be lost in the event of a
power failure.
LUN Logical Unit Number. A unique number by which a device is identified on the
SCSI bus. A tape drive has a fixed LUN of 0. In an autoloader, the changer
mechanism is LUN1.