NonStop S-Series System Expansion and Reduction Guide

Glossary
G-Series Common Glossary
Glossary-117
WORM
WORM. See write once, read many (WORM).
wormhole routing. A technique for reducing network latency in a router. Packet bytes are
immediately switched to the appropriate output port as soon as they arrive rather than
accumulated in a buffer until an entire packet is received. Contrast with store and
forward routing.
write once, read many (WORM). A media storage class in which data, once written, cannot
be erased or overwritten.
WWN. See worldwide name (WWN).
WWN zones. Similar to Ethernet virtual LANs (VLANs), WWN zones organize the cabling
and interactions between components in a storage and server system.
wye. A polyphase electrical supply where the conductors of the source transformer are
connected to the terminals in a physical arrangement that resembles the letter
Y. Each
point of the Y represents the connection for a conductor at high potential. The angle of
phase displacement between each point on the Y is 120 degrees. The center point of
the Y is the common return point for the neutral conductor.
wye-delta. The interconnections between a wye source and a delta load.
X.21. A digital signaling interface recommended by the International Telecommunications
Union, Telecommunication Standardization Sector (ITU-T) that includes specifications
for data terminal equipment/data communications equipment (DTE/DCE) physical
interface elements, alignment of call control characters and error checking, elements of
the call control phase for circuit switched services, data transfer at or below 9600
bits/second, and test loops.
X fabric. The X side of the internal or external ServerNet fabrics. See also fabric, external
ServerNet X or Y fabric, and internal ServerNet X or Y fabric.
XIO. See extensible input/output (XIO).
XLLINK. The linker program invoked during system generation to link accelerated (file code
100) TNS object files to create system code and system library files.
XO bond. The bond connection on an isolation transformer, installed between the
transformer’s neutral XO terminal and ground. This bond is required at North American
and British sites to provide an effective return path for any equipment conductor fault
current back to the neutral of the isolation transformer.
Y fabric. The Y side of the internal or external ServerNet fabrics. See also fabric, external
ServerNet X or Y fabric, and internal ServerNet X or Y fabric.
$YMIOP. The name of the maintenance I/O process that is built during system generation
and is available at system startup.