Glossary

active termination,	Terminates the SCSI bus with a series of resistors tied to +5 volts. The terminator is
regulated	labeled Regulated but is often referred to as an Active Terminator.

active-active	A pair of components, such as storage controllers in a failure-tolerant RAID array that
controllers	share a task or set of tasks when both are functioning normally. When one component of
	the pair fails, the other takes the entire load. Dual active controllers (also called dual-
	active controllers) are connected to the same set of devices and provide a combination of
	higher I/O performance and greater failure tolerance than a single controller.

ANSI	American National Standards Institute

automatic rebuild	A process where data is automatically reconstructed after a drive failure and written to a
	standby (spare) drive. An automatic rebuild will also occur when a new drive is installed
	manually in place of a failed drive. If the rebuild process is interrupted by a reset, use the
	Rebuild command on the Array Administration menu to restart the rebuilding process.

background rate	The background rate is the percentage of available array controller CPU time assigned to
	array administration activities, such as rebuilding failed drives, checking parity, and
	initialization. If the background rate is set to 100%, the array administration activities
	have a higher priority than any other array activity. At 0%, the array administration
	activity is done only if there is no other activity on the array controller.

bandwidth	A measure of the capacity of a communication channel, usually specified in MB/second.

cache	Memory on the RAID controller card, which permits intermediate storage of, read and
	write data without physically reading/writing from/to the disk, which can increase overall
	performance under certain conditions.

caching	Allows data to be stored in a pre-designated area of a disk or RAM (random access
	memory). Caching is used to speed up the operation of RAID arrays, disk drives,
	computers and servers, or other peripheral devices.

CH	Channel

channel	Any path used for the transfer of data and control information between storage devices
	and a storage controller or I/O adapter. Also refers to one SCSI bus on a disk array
	controller. Each disk array controller provides at least one channel.

CISPR	International Special Committee on Radio Interference

CLI	Command line interface.

concatenated	Inside the same drive array enclosure, a single contiguous drive channel supporting 12
channel	drives concurrently

device name	Software device address that identifies the controller/LUN, such as cXtYdZs0, where X is
	the host bus adapter, Y is the controller, and Z is the LUN. s0 slice number is used by the
	system, not by RAID Manager.

disk array	Two or more drives configured as a Drive Group (see next).

drive group	A physical set of drives configured as an array. Drive groups are defined during
	configuration.

EMU	Event Monitoring Unit

expansion drive	An enclosure containing a group of drives, power supplies, cooling fans, I/O cards, and
array	mid-planes (no RAID controller/controllers); generally, an external drive array that is used
	to daisy chain to an existing hardware based RAID configuration.

failover	A mode of operation for failure-tolerant arrays in which a component has failed and its
	function has been assumed by a redundant component.

Dot Hill Systems 200 manual Glossary

Models: 200

Glossary