Chapter 2: Introduction To Raid; Raid Description; Raid Benefits; Raid Functions - Lenovo ThinkServer RD330 Software User's Manual

MegaRAID SAS Software User Guide
Chapter 2
Introduction to RAID
This chapter describes Redundant Array of Independent Disks (RAID), RAID functions
and benefits, RAID components, RAID levels, and configuration strategies. In addition, it
defines the RAID availability concept, and offers tips for configuration planning.
2.1

RAID Description

2.2

RAID Benefits

2.3

RAID Functions

2.4 Components and
Features
RAID is an array, or group, of multiple independent physical drives that provide high
performance and fault tolerance. A RAID drive group improves I/O (input/output)
performance and reliability. The RAID drive group appears to the host computer as a
single storage unit or as multiple virtual units. I/O is expedited because several drives
can be accessed simultaneously.
RAID drive groups improve data storage reliability and fault tolerance compared to
single-drive storage systems. Data loss resulting from a drive failure can be prevented
by reconstructing missing data from the remaining drives. RAID has gained popularity
because it improves I/O performance and increases storage subsystem reliability.
Virtual drives are drive groups or spanned drive groups that are available to the
operating system. The storage space in a virtual drive is spread across all of the drives in
the drive group.
Your drives must be organized into virtual drives in a drive group and they must be able
to support the RAID level that you select. Below are some common RAID functions:

Creating hot spare drives
 Configuring drive groups and virtual drives
 Initializing one or more virtual drives
 Accessing controllers, virtual drives, and drives individually
 Rebuilding failed drives
 Verifying that the redundancy data in virtual drives using RAID level 1, 5, 6, 10, 50, or
60 is correct
 Reconstructing virtual drives after changing RAID levels or adding a drive to a drive
group
 Selecting a host controller to work on
RAID levels describe a system for ensuring the availability and redundancy of data
stored on large disk subsystems. See
about RAID levels. The following subsections describes the components of RAID drive
groups and RAID levels.

Chapter 2: Introduction to RAID

Section 2.5, RAID Levels for detailed information
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RAID Description
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