Raid Storage Introduction

RAID - which means Redundant Array of Inexpensive Disks, or sometimes people called it Redundant Array of Independent Disks - is a technology that employs the simultaneous use of two or more hard disk drives to achieve higher levels of performance, reliability, and / or larger volume of data sizes.

"RAID" is now used as a general term for computer data storage schemes that can divide and replicate data across multiple hard drives. RAID have a few different models and all invoke two key objectives: increase the reliability of data and increased input / output performance. When multiple physical disks are in place to use RAID technology, they are said to be in a RAID array. This array distributes data to multiple disks, but the array is viewed by a user of computer and operating system as a single disc. RAID can be set up to serve several different purposes.

The idea of RAID is to take the conventional disks in personal computers and combine them together in parallel. The assembly gives you the low cost of discs produced in large volume, the more reliable and a multiplier on the performance of individual disks.

The host adapter (often called a RAID controller) is between a high rate of data streams (on the computer side) and several low flow rates (on the side of the disc). When the computer writes to the disk, the host adapter takes high-speed data and breaks it into several streams in sync, one for each disc in a process called striping. Reads by the computer cause the host adapter to a stream of data for each disc, the multiplex flow in a stream, and send the resulting flow on the computer.