HP C1537A, Technical Reference Manual

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glossary 57
gl
os
sa
ry
host The host computer system acting as controller for the drive.
load The process in which the drive takes in an inserted cartridge and goes online.
LUN Logical Unit Number, by which different devices at a particular SCSI ID can
be addressed individually. The drive has a fixed LUN of 0.
LVD Low-Voltage Differential. See
SCSI
.
offline The drive is offline if the tape is currently unloaded or not in the drive. The
host has limited access, and cannot perform any commands that would cause
tape motion. The host can, however, load a tape, if one is inserted, and can
execute any diagnostic tests that do not require tape motion.
online The drive is online when a tape is loaded. The host has access to all command
operations, including those that access the tape, set configurations and run
diagnostic tests.
RAW see
read-after-write
read-after-write RAW improves data integrity by reading data immediately after it is written
and writing the data again if an error is found.
SCSI Small Computer System Interface—a standard command specification and
command set that enables computers and peripherals to communicate with
each other. HP’s Ultrium drives adhere to the SCSI specifications (see
Chapter 1, “Interface Implementation” in Volume 3, The SCSI Interface, of the
HP Ultrium Technical Manual) and support all features required by those
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.
With
low voltage differential (LVD) signaling, signals travel along two wires
and the difference in voltage between the wire pairs determines the signal
value. This enables faster data rates and longer cabling with less susceptibility
to noise than SE signaling and reduced power consumption.
Narrow and Wide, Fast, Ultra and Ultra2 SCSI