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Lesson 8 RAID basics
Objective Explain basic concepts related to RAID

Basic Concepts related to RAID

RAID (Redundant Array of Inexpensive Disks) is a valuable tool that combines data redundancy with improved performance and reduced cost. It enables you to write to several distinct disks as one drive. This decreases costs for an organization by allowing many inexpensive drives to act as one large logical drive. Depending on the needs of an organization, an appropriate RAID level can be chosen to support duplication of data, increased access speed, or minimized expense. RAID's advantages include:
  1. Combining multiple disks to create a single logical disk
  2. Minimizing the effect of a single drive failure
  3. Increasing performance in some instances
The next lesson describes RAID levels.

Creating RAID Arrays

In addition to supporting hardware RAID solutions, Red Hat Enterprise Linux supports software RAID. There are two ways that software RAID arrays can be created:
  1. While installing Red Hat Enterprise Linux
  2. After Red Hat Enterprise Linux has been installed
The following sections review these two methods.

While Installing Red Hat Enterprise Linux

During the normal Red Hat Enterprise Linux installation process, RAID arrays can be created. This is done during the disk partitioning phase of the installation.
To begin, you must manually partition your disk drives using Disk Druid. You must first create a new partition of the type "software RAID." Next, select the disk drives that you want to be part of the RAID array in the Allowable Drives field. Continue by selecting the desired size and whether you want the partition to be a primary partition.
Once you have created all the partitions required for the RAID array(s) that you want to create, you must then use the RAID button to actually create the arrays. You are then presented with a dialog box where you can select the array's mount point, file system type, RAID device name, RAID level, and the "software RAID" partitions on which this array is to be based.
Once the desired arrays have been created, the installation process continues as usual.