ServerNet Cluster 6780 Operations Guide (G06.28+, H06.05+)

Glossary
ServerNet Cluster 6780 Operations Guide—525606-003
Glossary-30
tetrahedral topology
tetrahedral topology. A topology of NonStop S-series servers in which the ServerNet
connections between the processor enclosures form a tetrahedron. See also topology.
TF. See time factor (TF).
time factor (TF). A number assigned to a line, path, or route to indicate efficiency in
transporting data. The lower the time factor, the more efficient the line, path, or route.
See also super time factors (STFs).
topology. The physical layout of components that define a local area network (LAN), wide
area network (WAN), or ServerNet communications network. See also layered
topology, star topology, split-star topology, and tri-star topology.
topology branch. A processor enclosure and the I/O enclosures attached to it.
Transmission Control Protocol over Internet Protocol (TCP/IP). A set of layered
communications protocols for connecting workstations and larger systems.
tri-star topology. A network topology that uses up to three cluster switches for each
external fabric. External routing is implemented between the three star groups of a
ServerNet cluster. (A star group consists of the eight nodes attached to one set of
cluster switches.) The star groups are joined by two-lane links. Introduced with the
G06.14 RVU, the tri-star topology supports up to 24 nodes. A tri-star topology requires
HP NonStop Cluster Switches (model 6770). See also star topology and split-star
topology.
UCME. See uncorrectable memory error (UCME).
unattended site. A computer environment where no operator resides on site and the only
access is from a central monitoring station.
uncorrectable memory error (UCME). An error caused by incorrect data at a particular
memory location. The cause of the error is such that the error is not automatically
corrected by the system, and memory replacement is required. Contrast with
correctable memory error (CME).
uninterruptible power supply (UPS). A source of power, external to a device, capable of
supplying continuous power to the device in the event of a power failure.
unplanned outage. Time during which a system is not capable of doing useful work
because of an unplanned interruption. Unplanned interruptions can include failures
caused by faulty hardware, operator error, or disaster.
UPS. See uninterruptible power supply (UPS)
.
volume. A logical disk drive, which can be one or two physical disk drives. In NonStop S-
series systems, volumes have names that begin with a dollar sign ($), such as $DATA.
See also mirrored disk or volume
.