Lenovo ThinkServer RD330 MegaRAID SAS Software User Guide - Page 21
Introduction to RAID
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MegaRAID SAS Software User Guide Chapter 2: Introduction to RAID | RAID Description 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 Section 2.5, RAID Levels for detailed information about RAID levels. The following subsections describes the components of RAID drive groups and RAID levels. Page 21