Lenovo System x3500 M4 - Memory Mirrored Channel

Memorymirroredchannel
MemorymirroredchannelmodereplicatesandstoresdataontwopairsofDIMMswithintwochannels
simultaneously.Ifafailureoccurs,thememorycontrollerswitchesfromtheprimarypairofmemoryDIMMs
tothebackuppairofDIMMs.
YoucanenablememorymirroredintheSetuputility(see“StartingtheSetuputility”onpage107).
Whenyouusethememorymirroredchannelfeature,considerthefollowinginformation:
•Whenyouusememorymirroredchannel,youmustinstallapairofDIMMsatatime.ThetwoDIMMsin
eachpairmustbeidenticalinsize,type,andrank(single,dual,orquad),andorganization,butnotin
speed.ThechannelsrunatthespeedoftheslowestDIMMinanyofthechannels.
•Themaximumavailablememoryisreducedtohalfoftheinstalledmemorywhenmemorymirroredis
enabled.Forexample,ifyouinstall64GBofmemoryusingRDIMMs,only32GBofaddressablememory
isavailablewhenyouusememorymirroredchannel.
ThefollowingdiagramliststheDIMMconnectorsoneachmemorychannel.
DIMM 3 DIMM 9 DIMM 6 DIMM 12 DIMM 2 DIMM 8 DIMM 5 DIMM 11 DIMM 1 DIMM 7 DIMM 4 DIMM 10
Microprocessor 1
DIMM 15 DIMM 21 DIMM 18 DIMM 24 DIMM 14 DIMM 20 DIMM 17 DIMM 23 DIMM 13 DIMM 19 DIMM 16 DIMM 22
Microprocessor 2
Channel
Channel
Figure42.Connectorsoneachmemorychannel
Note:YoucaninstallDIMMsformicroprocessor2assoonasyouinstallmicroprocessor2;youdonothave
towaituntilalloftheDIMMconnectorsformicroprocessor1arefilled.
Thefollowingtableshowstheinstallationsequenceformemorymirroredmode:
Table6.MemorymirroredchannelmodeDIMMpopulationsequence
NumberofDIMMs
Numberofinstalled
microprocessorDIMMconnector
FirstpairofDIMMs
11,4
SecondpairofDIMMs
19,12
ThirdpairofDIMMs
12,5
FourthpairofDIMMs
18,11
FifthpairofDIMMs
17,10
SixthpairofDIMMs
13,6
64Systemx3500M4InstallationandServiceGuide