Lenovo System x3550 M4 - Page 63

Ifafailureoccurs,thememorycontrollerswitchesfromtheprimarypairofmemoryDIMMstothebackup
pairofDIMMs.ToenablememorymirroredchannelthroughtheSetuputility,selectSystemSettings➙
Memory.Formoreinformation,see“UsingtheSetuputility”onpage97
.Whenyouusethememory
mirroredchannelfeature,considerthefollowinginformation:
•Whenyouusememorymirroredchannel,youmustinstallapairofDIMMsatatime.ThetwoDIMMsin
eachpairmustbeidenticalinsize,type,andrank(single,dual,orquad),andorganization,butnotin
speed.ThechannelsrunatthespeedoftheslowestDIMMinanyofthechannels.
•Themaximumavailablememoryisreducedtohalfoftheinstalledmemorywhenmemorymirrored
channelisenabled.Forexample,ifyouinstall64GBofmemoryusingRDIMMs,only32GBof
addressablememoryisavailablewhenyouusememorymirroredchannel.
•ForUDIMMs,DIMMconnectors3,6,7,and10formicroprocessor1andDIMMconnectors15,18,19,
and22formicroprocessor2arenotusedinmemorymirroredchannelmode.
ThefollowingdiagramliststheDIMMconnectorsoneachmemorychannel.
Figure36.Connectorsoneachmemorychannel
Thefollowingtableshowstheinstallationsequenceformemorymirroredchannelmode:
Table7.MemorymirroredchannelmodeDIMMpopulationsequence
NumberofDIMMs
Numberofinstalled
microprocessorDIMMconnector
FirstpairofDIMMs
11,4
SecondpairofDIMMs
19,12
ThirdpairofDIMMs
12,5
FourthpairofDIMMs
18,11
FifthpairofDIMMs
13,6
SixthpairofDIMMs
17,10
SeventhpairofDIMMs
213,16
EighthpairofDIMMs
221,24
NinthpairofDIMMs
214,17
TenthpairofDIMMs
220,23
EleventhpairofDIMMs
215,18
TwelfthpairofDIMMs
219,22
DIMMconnectors3,6,7,10,15,18,19,and22arenotusedinmemorymirroredchannelmodewhenUDIMMs
areinstalledintheserver.
Chapter2.Installingoptionaldevices49