RAID User Guide

RAID levels Function/Applications Advantages/Disadvantages
RAID Recovery
Function:
Identical (mirrored) data is
stored on two drives.
Boosts the functionality of
RAID 1 with valuable
features.
Applications:
Any application that requires
a simple data protection
method.
Advantages:
Provides high fault
tolerance.
Users can choose to mirror
data continuously or on
request.
Data recovery is quick and
easy.
Allows hot-plugging of
mirrored drive (with eSATA
or docking station hard
drive).
Enables easy migration to
non-RAID.
Disadvantages:
Only half of the total drive
capacity can be used for
storage.
Storage space may be
wasted if the capacities of
the primary and recovery
hard drives are different.
RAID 5
Function:
Distributes data across three
hard drives. If one hard drive
fails, RAID 5 allows data to
be recovered from the other
two hard drives.
Applications:
A good choice for large
amounts of critical data.
Advantages:
Data redundancy
Improved performance and
capacity
High fault-tolerance and
read performance
Disadvantages:
During a RAID rebuild after a
hard drive fails, system
performance can be
decreased.
Fault tolerance
Fault tolerance is the ability of a RAID array to withstand and recover from a drive failure. Fault
tolerance is provided by redundancy. Therefore, RAID 0 has no fault tolerance because it does not
copy data to another hard drive. With RAID 1 and Recovery, one drive can fail without causing the
array to fail. With Recovery, however, the restoration of a single file or an entire hard drive is much
simpler than with RAID 1 alone. With RAID 5, one of the three hard drives can fail without causing the
array to fail.
RAID modes supported 5