Software Raid Configuration; Understanding Raid Levels; Raid 0 - Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010 Administration Manual

Software RAID Configuration

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The purpose of RAID (redundant array of independent disks) is to combine several hard disk
partitions into one large virtual hard disk to optimize performance, data security, or both. Most
RAID controllers use the SCSI protocol because it can address a larger number of hard disks in a
more effective way than the IDE protocol and is more suitable for parallel processing of commands.
There are some RAID controllers that support IDE or SATA hard disks. Software RAID provides the
advantages of RAID systems without the additional cost of hardware RAID controllers. However,
this requires some CPU time and has memory requirements that make it unsuitable for real high
performance computers.
IMPORTANT: Software RAID is not supported underneath clustered file systems such as OCFS2,
because RAID does not support concurrent activation. If you want RAID for OCFS2, you need the
RAID to be handled by the storage subsystem.
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SUSE Linux Enterprise offers the option of combining several hard disks into one soft RAID
system. RAID implies several strategies for combining several hard disks in a RAID system, each
with different goals, advantages, and characteristics. These variations are commonly known as
RAID levels.
Section 8.1, "Understanding RAID Levels," on page 79
Section 8.2, "Soft RAID Configuration with YaST," on page 80
Section 8.3, "Troubleshooting," on page 82
Section 8.4, "For More Information," on page 82

8.1 Understanding RAID Levels

This section describes common RAID levels 0, 1, 2, 3, 4, 5, and nested RAID levels.
Section 8.1.1, "RAID 0," on page 79
Section 8.1.2, "RAID 1," on page 80
Section 8.1.3, "RAID 2 and RAID 3," on page 80
Section 8.1.4, "RAID 4," on page 80
Section 8.1.5, "RAID 5," on page 80
Section 8.1.6, "Nested RAID Levels," on page 80

8.1.1 RAID 0

This level improves the performance of your data access by spreading out blocks of each file across
multiple disk drives. Actually, this is not really a RAID, because it does not provide data backup, but
the name RAID 0 for this type of system has become the norm. With RAID 0, two or more hard
disks are pooled together. The performance is very good, but the RAID system is destroyed and your
data lost if even one hard disk fails.
Software RAID Configuration
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