Thecus N8810U series, Руководство пользователя

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Appendix B: RAID Basics
Overview
A Redundant Array of I n dependent Disks ( RAI D) is an array of sev eral hard disks
t hat provide dat a secu rit y and high perform an ce. A RAI D syst em accesses sev eral
hard disks sim ult aneously, w hich im proves I / O per form ance over a single hard disk.
Dat a securit y is enhanced by a RAI D, since dat a loss due t o a hard disk failure is
m inim ized by r egen erat ing redundant dat a fr om t he ot h er RAI D hard disks.
Benefits
RAI D im proves I / O perform ance, and increases dat a securit y t hrough fault
t olerance and r edundant dat a st orage.
Improved Performance
RAI D pr ovides access t o several hard disk drives sim ult aneously, w hich great ly
increases I / O perfor m ance.
Data Security
Hard disk drive failure unfort unat ely is a com m on occur r ence. A RAI D helps prevent
against t he loss of dat a due t o hard disk failure. A RAI D offer s addit ional hard disk
drives t hat can avert dat a loss from a hard disk drive failure. I f a hard drive fails,
t he RAI D volum e can r egenerat e dat a from t he dat a and parit y st or ed on it s ot her
hard disk drives.
RAID Levels
The Thecus I P st orage support s st andard RAI D lev els 0, 1 , 5 , 6 , 10, 50, 60 and JBOD.
You ch oose a RAI D lev el w hen y ou creat e a sy st em v olum e. Th e fact ors for
select ing a RAI D level are:
•
Your r equirem ent s for per form ance
•
Your n eed for dat a secu rit y
•
Num ber of hard disk drives in t he sy st em , capacit y of hard disk drives in t he
syst em
The following is a descript ion of each RAI D lev el:
RAI D 0
RAI D 0 is best suit ed for applicat ions t hat need high bandwidt h but do not r equire
a high level of dat a securit y. The RAI D 0 lev el provides t he best per form ance of all
t he RAI D lev els, but it does not provide dat a r edundancy.
RAI D 0 uses disk st riping and breaking up dat a int o blocks t o w rit e across all hard
drives in t he v olum e. Th e sy st em can t hen use m ult iple hard drives for fast er r ead
and w rit e. The st ripe size par am et er t hat w as set w hen t h e RAI D w as creat ed
det erm ines t he size of each block. No parit y calculat ions com plicat e t he w rit e
operat ion.
RAI D 1
RAI D 1 m irrors all dat a from on e hard disk drive t o a second one hard disk drive,
t hus providing com plet e dat a r edundancy. How ev er, t he cost of dat a st orage
capacit y is doubled.
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