Raid faq

7
FAQ | RAID
RAID 60–orRAID6+0createsasinglestripedvolumeacrosstwoRAID6arrays,essentiallycombiningblock-level
stripingofRAID0withthedoubledistributedparityofRAID6.Itrequiresaminimumof6disks.Itprovidesbetterdata
redundancy,betterdataintegrityandthecapabilitytotolerateupto2diskfailuresperRAID6arraybeforedataislost.
Raidcongurationsupportvariesbycontroller.Seethecontrollersectionbelowforspecicsupportdetails.
What is the value of a battery backed RAID controller?
EnablingthecontrollercacheallowsthecontrollertoacknowledgereceiptofthedatabeforeitiswrittentotheRAID
arraytoimproveperformance.Thismayputdataatriskinthecaseofasuddenpowerloss.Somecontrollers,likethe
9270-8i,supportabatterybackupunit(BBU)whichprotectsthedatainthecontrollercacheinthecaseofasudden
powerloss.Ifpowerlossisaconcern,eitherthecontrollercacheshouldbedisabledoraBBUshouldbeconsidered.
What are the dierences between the 9217, 9270 & 2308 LSI controllers?
The LSI 9217-4i4eisaHostBusAdapter(HBA).IthaslimitedRAIDcapabilitiesandtheprimarypurposeistoprovide
supportforSASdrivesbutitalsosupportsSATAdrives.The9217-4i4esupportsthefollowingRAIDlevels:0,1,10,1E.
The LSI 2308isanI/Ocontroller(IOC).IthaslimitedRAIDcapabilitiesandtheprimarypurposeistoprovidesupportfor
SASdrivesbutitalsosupportsSATAdrives.TheLSI2308supportsthefollowingRAIDlevels:0,1,10,1E.
The LSI 9270-8iisanHBAthathasaRAID-on-chip(ROC)processoronboard.IthassubstantialRAIDcapabilitiesas
comparedtothe9217-4i4eandtheLSI2308.TheprimarypurposeofthiscardissupportingSASandSATARAIDarrays.
TheLSI9270-8isupportsthefollowingRAIDlevels:0,1,5,6,10,50,60.Italsosupportsabatterybackupforthedata
cache on the controller.
A
B
C
D
E
F
Logical disk
Striping
A – L
C
D
A
B
M
N
M – X
E
F
O
P
Q
R
Parity Parity Parity Parity ParityParity
I
J
G
H
S
T
K
L
U
V
W
X
Parity Parity Parity Parity ParityParity
RAID6array RAID6array
RAID 60 disk array