Glossary, Continued

Format

The process of writing zeros to all data fields in a physical drive (hard drive) to map out

 

unreadable or bad sectors. Because most hard drives are factory formatted, formatting is

 

usually only done if a hard disk generates many media errors.

GB

Shorthand for 1,000,000,000 (10 to the ninth power) bytes. It is the same as 1,000 MB

 

(megabytes).

Host-based Array A disk array with an Array Management Software in its host computer rather than in a disk subsystem.

Host Computer Any computer that disks are directly attached to. Mainframes, servers, workstations, and personal computers can all be considered host computers.

Hot Spare A stand-by drive ready for use if another drive fails. It does not contain any user data. Up to eight disk drives can be assigned as hot spares for an adapter. A hot spare can be dedicated to a single redundant array or it can be part of the global hot-spare pool for all arrays controlled by the adapter.

Hot Swap The substitution of a replacement unit in a disk subsystem for a defective one, where the substitution can be performed while the subsystem is running (performing its normal functions). Hot swaps are manual.

I/O Driver A host computer software component (usually part of the operating system) that controls the operation of peripheral controllers or adapters attached to the host computer. I/O drivers communicate between applications and I/O devices, and in some cases participates in data transfer.

Initialization The process of writing zeros to the data fields of a logical drive and generating the corresponding parity to put the logical drive in a Ready state. Initializing erases previous data and generates parity so that the logical drive will pass a consistency check. Arrays can work without initializing, but they can fail a consistency check because the parity fields have not been generated.

Cont’d

124MegaRAID Express 500 Hardware Guide