128 Installing System ComponentsMemory Sparing SupportMemory sparing is supported in single- or dual-processor systems that have oneof the fully populated memory configurations shown in Table 3-1. The memorysparing feature must be enabled in the Memory Information screen of theSystem Setup program. See "Entering the System Setup Program" on page 43.To use memory sparing, you must disable node interleaving.Memory sparing is applied independently to the two groups of DIMMs on thesame sides of the processor sockets. To support memory sparing, all DIMMsockets within a DIMM group must be populated.When enabled, memory sparing allocates and reserves ranks of memory fromthe installed DIMMs to act as spare memory in the event of a memorychannel failure. A memory channel uses paired DIMMs; for memory sparingto work, DIMMs must be paired as spares also.Memory sparing allocates only the first rank of memory of a DIMM. For asingle-rank DIMM, the entire capacity of the DIMM must be allocated forsparing along with the adjacent single-rank DIMM to spare a memoryTable 3-1. Memory ConfigurationsTotal System Memory DIMM SocketSingle-ProcessorSystemDual-ProcessorSystemDIMM A1/DIMM B1DIMM A2/DIMM B2DIMM A3/DIMM B3DIMM A4/DIMM B41 GB 2 GB 512 MB 512 MB2 GB 4 GB 512 MB 512 MB 512 MB 512 MB2 GB 4 GB 1 GB 1 GB4 GB 8 GB 1 GB 1 GB 1 GB 1 GB4 GB 8 GB 2 GB 2 GB6 GB 12 GB 2 GB 2 GB 1 GB 1 GB8 GB 16 GB 2 GB 2 GB 2 GB 2 GB8 GB 16 GB 4 GB 4 GB12 GB 24 GB 4 GB 4 GB 2 GB 2 GB16 GB 32 GB 4 GB 4 GB 4 GB 4 GB
