The following table lists the DIMM connectors on each memory channel.Table 12. Connectors on each memory channelMemory channel DIMM connectorsChannel 0 2, 3, 10, 11Channel 1 5, 6, 13, 14Channel 2 7, 8, 15, 16Memory mirroringMemory-mirroring mode replicates and stores data on two pairs of DIMMs withintwo channels simultaneously. If a failure occurs, the memory controller switchesfrom the primary pair of memory DIMMs to the backup pair of DIMMs. You mustenable memory mirroring through the Setup utility. For details about enablingmemory mirroring, see “Using the Setup utility” on page 235. When you use thememory mirroring feature, consider the following information:v To support memory mirroring, the DIMMs in each pair must match but the pairscan be different from each other. For example, the first pair of DIMMs mustmatch and the second pair of DIMMs must match; however, the DIMM type forthe first and second pair of DIMMs can be different from each other.v The maximum available memory is reduced to half of the installed memory whenmemory mirroring is enabled. For example, if you install 64 GB of memory, only32 GB of addressable memory is available when you use memory mirroring.v Channel 2 DIMM connectors 8 ,7, 15, and 16 are not used in memory-mirroringmode.The following table lists the installation sequence for installing DIMMs inmemory-mirroring mode.Table 13. Memory-mirroring mode DIMM population sequenceDIMMsNumber of installedmicroprocessors DIMM connectorFirst pair of DIMMs 1 3, 6Second pair of DIMMs 1 2, 5Fourth pair of DIMMs 2 14, 11Fifth pair of DIMMs 2 13, 10Note: DIMM connectors 7, 8, 15, and 16 are not used in memory-mirroring mode.When you install or remove DIMMs, the server configuration information changes.When you restart the server, the system displays a message that indicates that thememory configuration has changed.Online-spare memoryThe memory online-spare feature disables the failed memory from the systemconfiguration and activates an online-spare DIMM to replace the failed active DIMM.You can enable either online-spare memory or memory mirroring in the Setup utility(see “Using the Setup utility” on page 235). When you use the memory online-sparefeature, consider the following information:v The memory online-spare feature is supported on server models with an IntelXeon ™ 5600 series microprocessor.v When you enable the memory online-spare feature, you must install three DIMMsper microprocessor at a time. The first DIMM must be in channel 0, the secondChapter 5. Removing and replacing server components 165
