HP C7401A - SureStore Ultrium 230 Tape Drive Technical Reference Manual page 36

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.
A mark written by the host to the tape that can be searched for, often using
filemark
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.
A mode of responding to SCSI commands where the drive or other peripheral
immediate mode
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 command. On the
WRITE FILEMARKS
other hand, data is not flushed to tape in response to a filemark command.
By default, the buffer in the drive is flushed every 5 seconds. Infinite flush
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.
Logical Unit Number. A unique number by which a device is identified on the
LUN
SCSI bus. A tape drive has a fixed LUN of 0. In an autoloader, the changer
mechanism is LUN1.
Small Computer System Interface—a standard command specification and
SCSI
command set that enables computers and peripherals to communicate with
each other. HP's Ultrium drives adhere to the SCSI-3 specification and
support all features required by that standard.
Single-Ended and Low Voltage Differential SCSI
These terms define how the signals are transmitted along the cable.
With single-ended (SE) SCSI, each signal travels over a single wire and each
signal's value is determined by comparing the signal to a paired ground wire.
Signal quality tends to decrease over longer cable lengths or at increased
signal speed.
36 Glossary