HP StorageWorks 8000 - NAS User Manual page 254

Glossary
GBIC (Gigabit Interface Converter)
A transceiver that converts electric currents (digital highs and lows) to optical signals, and optical
signals to digital electric currents. The GBIC is typically employed in fiber optic and Ethernet
systems as an interface for high-speed networking. The data transfer rate is one gigabit per second
(1 Gbps) or more.
Group Identification (GID)
A number in the UNIX environment that identifies a group of individuals or services to a computer
system.
Group quota
Lets you restrict the space usage on the NAS server for groups.
Heartbeat
A periodic signal generated by the server to indicate that it is still running.
High availability
High availability characterizes a system that is designed to avoid the loss of service by reducing or
managing failures and minimizing downtime. High availability implies a service level in which
both planned and unplanned downtime does not exceed a small stated value.
Host Bus Adapter (HBA)
An HBA is an I/O adapter that sits between the host computer's bus and the Fibre Channel loop
and manages the transfer of information between the two channels. In order to minimize the
impact on host processor performance, the host bus adapter performs many low-level interface
functions automatically or with minimal processor involvement.
Hot swapping
A feature that allows equipment to be connected to an active device, such as a computer, while the
device is powered on.
Hub
A communications infrastructure device to which nodes on a multi-point bus or loop are physically
connected. Commonly used in Ethernet and Fibre Channel networks to improve the manageability
of physical cables. Hubs maintain the logical loop topology of the network of which they are a
part, while creating a "hub and spoke" physical star layout. Unlike switches, hubs do not aggregate
bandwidth. Hubs typically support the addition or removal of nodes from the bus while it is
operating.
254 HP StorageWorks NAS 8000 User's Guide