User manual

Knowledge Base

What is RAID?

RAID, short for Redundant Array of Independent Disks, is storage conﬁguration that

combines two or more disks for the purpose of providing fault tolerance and/or im-

proving performance. There are several different conﬁgurations or levels of RAID,

each providing a different method of sharing or distributing data among the drives.

RAID 0

RAID 0 provides data striping, which spreads out

blocks of data over all drives, but does not provide

data redundancy. Although performance is im-

proved, the lack of fault tolerance means that if one

drive fails, all data in the array will be lost.

RAID 1

RAID 1 provides mirroring over multiple disks

with the same read/write speed of a single disk.

A RAID 1 array can only be as large as its small-

est member disk. Because the data is stored on

multiple disks, RAID 1 provides fault tolerance

and protection.

RAID 5

RAID 5 provides data striping with distributed par-

ity, which stores information that can be used to

reconstruct data. A RAID 5 array will be the size

of all the combined disks capacity less the capac-

ity of one disk. For example, if there are 4x 500GB

disks in the array, the array capacity will be 1.5TB

(3x500GB). RAID 5 allows the array to continue op-

erating even if one of the disks fails. The diagram

below indicates the operation of RAID 5:

RAID 6

RAID 6 is an extension of RAID 5. It adds an ad-

ditional parity block by using block-level striping

with two parity blocks distributed across all the

member disks. RAID 6 allows the array to con-

tinue operating even if two of the disks fail. The

diagram below indicates the operation of RAID 6:

Product

Overview

Installation

Web

Conﬁguration

Knowledge

Base