IBM TotalStorage DS300 Best Practices Manual page 658

Transmission Control Protocol A
communications protocol used in the Internet and in
any network that follows the Internet Engineering
Task Force (IETF) standards for Internetwork
protocol. TCP provides a reliable host-to-host
protocol between hosts in packet-switched
communications networks and in interconnected
systems of such networks. It uses the Internet
Protocol (IP) as the underlying protocol.
U
UNIX A highly portable operating system
originally developed by Bell Laboratories that
features multiprogramming in a multiuser
environment. UNIX is implemented in the C
language. UNIX was originally developed for use on
minicomputers but has been adapted on
mainframes and microcomputers. It is especially
suitable for multiprocessor, graphics, and
vector-processing systems.
V
vDisk See Virtual Disk.
Virtual Disk An SVC device that appears to host
systems attached to the SAN as a SCSI disk. Each
vDisk is associated with exactly one I/O group.
Virtualization An abstraction of storage where the
representation of a storage unit to the operating
system and applications on a server is divorced from
the actual physical storage where the information is
contained.
W
WAN Wide Area Network.
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IBM TotalStorage DS300 and DS400 Best Practices Guide
Wave Division Multiplexing
simultaneous transmission of a number of data
streams over the same physical fiber, each using a
different optical wavelength. WDM receives
incoming optical signals from many sources (Fibre
Channel, IP, ESCON, FICON) which it converts to
electrical signals, it then assigns them a specific
wavelength (or lambdas) of light and retransmits
them on that wavelength. This method relies on the
large number of wavelengths available within the
light spectrum. Coarse WDM (CWDM) and Dense
WDM (DWDM) are based on the same methodology
as WDM enabling more data streams over the same
physical fiber.
WDM See Wave Division Multiplexing.
World Wide Name A unique number assigned to
Fibre Channel devices (including hosts and adapter
ports) - analogous to a MAC address on a network
card.
WWN See World Wide Name.
Z
Zoning In Fibre Channel environments, zoning
allows for finer segmentation of the switched fabric.
Zoning can be used to instigate a barrier between
different environments. Ports that are members of a
zone can communicate with each other but are
isolated from ports in other zones. Zoning can be
implemented in two ways: hardware zoning and
software zoning.
WDM allows the