mode, see “Non-mirroring (independent mode).” For more information andDIMM population for memory mirroring, see “Memory mirroring.” For moreinformation and DIMM population for memory sparing, see “Memory sparing”on page 45.Non-mirroring (independent mode)When you use non-mirroring mode, follow the DIMM population sequence asindicated in the following table..Note: When you install an optional microprocessor and memory expansion tray inthe server, microprocessors 3 and 4 must be installed as a pair. The server does notsupport a configuration of three microprocessors.Table 8. DIMM population sequence for non-mirroring mode (independent mode)Number ofinstalledmicroprocessorsDIMM connector populationsequence on the system boardDIMM connector populationsequence on the microprocessorand memory expansion tray1 1, 12, 4, 9, 2, 11, 5, 8, 3, 10, 6, 72 1, 13, 12, 24, 4, 16, 9, 21, 2, 14, 11,23, 5, 17, 8, 20, 3, 15, 10, 22, 6, 18, 7,194 1, 13, 12, 24, 4, 16, 9, 21, 2, 14, 11,23, 5, 17, 8, 20, 3, 15, 10, 22, 6, 18, 7,1925, 37, 36, 48, 28, 40, 33, 45, 26, 38,35, 47, 29, 41, 32, 44, 27, 39, 34, 46,30, 42, 31, 43Memory mirroringMemory-mirroring replicates and stores data on DIMMs across two or fourchannels simultaneously. If a failure occurs, the memory controller switches fromthe DIMMs on the primary channel to the DIMMs on the backup channel. Toenable memory mirroring through the Setup utility, select System Settings →Memory → Memory Mode. For more information, see “Using the Setup utility” onpage 127.When you use memory mirroring mode, consider the following information:v The server supports single-socket memory mirroring. Memory channel 0 mirrorschannel 1, and memory channel 2 mirrors channel 3. This mirroring providesredundancy in memory but reduces the total memory capacity in half.v DIMMs must be installed in pairs for each microprocessor when using thememory mirroring feature.v The DIMM population must be identical for memory channel 0 and memorychannel 1, and identical for memory channel 2 and memory channel 3.v Memory mirroring reduces the maximum available memory by half of theinstalled memory. For example, if the server has 64 GB of installed memory, only32 GB of addressable memory is available when memory mirroring is enabled.v The following table lists the DIMM installation sequence for memory-mirroringmode.Note: The server does not support a configuration of three microprocessors. Theserver supports one, two, or four microprocessors only.44 System x3750 M4 Types 8722 and 8733: Installation and Service Guide
