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GEC. See Gigabit Etherchannel.
geographic cluster (GeoCluster). A cluster with remote mirroring. A highly available system consisting of two sites
that can be geographically distant from one another. This allows for continued availability in the case of the failure of
an entire site. Each site can contain one or two nodes, for a total of up to four nodes in the geographic cluster. The
sites communicate with each other over GeoNetworks. See also cluster, HACMP/XD, and GeoNetwork.
GeoNetwork. Ethernet path by which data is mirrored between the local and remote sites of a GeoCluster.
GHz. see gigahertz.
gigabyte (GB). In decimal notation, 1 073 741 824 when referring to memory capacity; in all other cases, it is
defined as 1 000 000 000.
Gigabit Etherchannel (GEC). A proprietary technology developed by Cisco that creates a team of two Gigabit
Ethernet adapters to increase transmission and reception throughput. Adapter fault tolerance is also supported by this
technology.
Gigabit Interface Converter (GBIC). An encoding/decoding device that is a Class-1 laser component assembly with
transmitting and receiving receptacles that connect to fiber-optic cables.
gigahertz (GHz). A unit of measure of frequency. One gigahertz equals 1 000 000 000 hertz.
GMD. GeoMirror devices (for example, remotely mirrored volumes).
H
HACMP. see high availability cluster multiprocessing.
high availability cluster multiprocessing (HACMP). An AIX Licensed Program Product (LPP) that provides
clustering function. An HACMP cluster can include up to 32 nodes.
HACMP/XD. see high availability cluster multiprocessing extended distance.
high availability cluster multiprocessing/extended distance (HACMP/XD). An AIX Licensed Program Product
(LPP) that provides the capability for mirroring data across TCP/IP point-to-point networks over an unlimited distance
from one geographic site to another.
heartbeat. Also called Keepalive. State-of-health message exchanged between nodes. Means of detecting failure in
a cluster.
high availability. A model for maintaining computer service availability. It views service availability not as a series of
replicated physical components, but rather as a set of system-wide, shared resources that cooperate to guarantee
essential services.
hertz (Hz). A unit of frequency equal to one cycle per second.
Note: In the United States, line frequency is 60 Hz or a change in voltage polarity 120 times per second; in Europe,
line frequency is 50 Hz or a change in voltage polarity 100 times per second.
host. (1) In TCP/IP, any system that has at least one Internet address associated with it. A host with multiple network
interfaces may have multiple Internet addresses associated with it. The host can be a client, a server, or both. (2) In
fibre-channel technology, any system that has at least one worldwide name associated with it. A host with multiple
network interfaces may have multiple worldwide names associated with it.
host processor. See host computer.
I
IDE. see integrated development environment.
integrated development environment (IDE). A set of software development tools such as source editors, compilers,
and debuggers, that are accessible from a single user interface.
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NAS Gateway 500 Administrator's Guide
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