Acer SmartRAID V Manual do Utilizador descarregar pdf (Página 243)

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Glossary

Controller

A device that controls the transfer of data

between a computer and a peripheral device.

For example, disk drives, video displays,

keyboards, and printers all require controllers.

The DPT SmartRAID V is a controller for disk

drives and disk arrays. See also, HBA.

DAE

Dynamic Array Expansion. A feature that

enables you to increase your storage capacity

under Windows NT by adding one or more

drives to your RAID 0 and RAID 5 arrays while

your system remains online.

Degraded Mode

The mode of operation of a redundant array in

which it can continue to be accessed after a

member drive has failed. For read accesses,

data is synthesized from the other drives in the

array. For write accesses, data is stored on the

remaining drives in such a way that it can be

restored when the failed drive is replaced.

Device

SCSI devices include peripherals such as disk

and tape drives, optical devices, scanners, and

printers. SCSI controllers are also considered

SCSI devices.

Differential

An electrical signal protocol which transmits

information through a current loop rather than

by changes in voltage, thereby reducing the

susceptibility to electrical interference. High

Voltage Differential SCSI uses RS485

transceivers to transfer data at distances up to

25 meters (82 feet). Low Voltage Differential

SCSI (Ultra2) achieves a 25 meter cable length

without the need for external transceivers.

Digital High Availability Fault Bus

A proprietary Compaq Corporation (formerly

Digital Equipment Corp.) bus standard that

provides signals to host adapters for remote

system management and device fault

notification.

DIMM

Dual In-line Memory Module. A standard

packaging for RAM on a small circuit board with

a defined edge connector. See also SIMM.

Dirty

Refers to a cache page in which data has been

written or modified but which has not yet been

copied to the storage device. When the data has

been copied to disk, the page is said to be clean.

DMA

Direct Memory Access. A method of data

transfer that allows data to be moved between a

peripheral controller and system memory

without interaction with the host CPU. The data

may be moved by the peripheral controller itself

or by a separate DMA controller.

Driver

A system level software module that receives I/

O requests from higher levels within the

operating system and converts those requests

to the protocol required by a specific hardware

device such as a peripheral adapter.

Dual Loop

A method of providing Fibre Channel controller

redundancy. By forming two arbitrated loops on

a dual channel controller and connecting the

devices to both loops, fault tolerance is provided

for cable failure. In normal operation, the

controller will use both loops to communicate

with the devices, which maximizes controller

bandwidth and performance.

EBDA

Extended BIOS Data Area. An area of system

RAM that may be used by controller devices to

store and execute their BIOS code. Standard

rules define the way in which devices must

share this space.

ECC

Error Correcting Code. A method of generating

redundant information (checksums), which can

be used to detect and correct bit errors in

stored or transmitted data.

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