Sony VAIO VGX-XL1 User Manual page 134

Improved Availability
Availability refers to your data being present and ready to use. A RAID system
improves availability by providing fault tolerance and by providing special
features that allow for recovery from hardware faults without disruption.
Increased and Integrated Capacity
RAID systems increase capacity by turning a number of smaller drives into a
larger array, thus combining or adding their individual storage capacities
together. This facilitates applications that require large amounts of contiguous
disk space, and also makes disk space management simpler. (However, a
percentage of total capacity is lost to overhead or redundancy in most
implementations.)
Improved Performance
RAID systems improve performance by allowing the controller to take full
advantage of the capabilities of multiple hard disk to get around performance-
limiting issues that plague individual hard disks. Different RAID
implementations improve performance in different ways and to different
degrees, but all improve performance in some way.
RAID Levels (Types)
Currently, Sony supports four different levels or types of RAID to implement
an array, using combinations of mirroring, striping, duplexing, and parity
technologies.
Each RAID level is independent and different, and no strict hierarchy should
be inferred from the specific number attached to a RAID level. In other words,
a RAID level that is "better" for one person may be "worse" for another.
Note: The software to perform the RAID-functionality and control the hard
disks can simply be a driver, or can be located on a separate hardware RAID
controller. Some Microsoft
tion for a lower cost option. Hardware RAID controllers cost more than pure
software, but can offer better performance.
What are the different RAID Levels?
A RAID array is made up of two or more hard disks working in parallel, which
appear and function as a single hard disk to the user. Sony has approved four
different RAID levels or types for use in VAIO
VGX-XL1 Digital Living System
®
operating systems include a software RAID solu-
®
computers.
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