Introduction; Raid Basics - HighPoint ATA-133 RAID User Manual

1.1 RAID Basics

RAID (Redundant Array of Independent Disks) is a method of combining
several hard drives(physical drives) into one logical unit(logical drive). Such
combining can offer either or both fault tolerance and higher data throughput
than a single hard drive.
There are usually a few methods through which hard drives can be combined
together. The different methods are refered as different RAID Levels. Different
RAID levels represent different performance level, security level and cost.
The most frequently used RAID levels include RAID 0, 1, 0+1 and 5. Also
there are some combined RAID levels, for example, RAID 0+1 is the combina-
tion of RAID 0 and RAID 1. Here is a briefing table of these popular RAID
levels:
Description
Data striping
RAID 0
Disk mirroring
RAID 1
RAID 0 and RAID 1
RAID
combined
0+1
Disk Spanning
JBOD
1-1
Minimum
# of Drives Benefits
Highest Performance
2
without data protection
Data protection through
2
redundancy
Highest performance with
4
data protection
No data protection and
2
performance improving,
but full usage of disk
space

Introduction