v When you use memory mirrored channel, you must install a pair of DIMMs at atime. The two DIMMs in each pair must be identical in size, type, and rank(single, dual, or quad), and organization, but not in speed. The channels run atthe speed of the slowest DIMM in any of the channels.v The maximum available memory is reduced to half of the installed memory whenmemory mirrored channel is enabled. For example, if you install 64 GB ofmemory using RDIMMs, only 32 GB of addressable memory is available whenyou use memory mirrored channel.v For UDIMMs, DIMM connectors 3, 6, 7, and 10 for microprocessor 1 and DIMMconnectors 15, 18, 19, and 22 for microprocessor 2 are not used in memorymirrored channel mode.The following diagram lists the DIMM connectors on each memory channel.The following table shows the installation sequence for memory mirrored channelmode:Table 8. Memory mirrored channel mode DIMM population sequenceNumber of DIMMsNumber of installedmicroprocessor DIMM connectorFirst pair of DIMMs 1 1, 4Second pair of DIMMs 1 9, 12Third pair of DIMMs 1 2, 5Fourth pair of DIMMs 1 8, 11Fifth pair of DIMMs 1 3, 6Sixth pair of DIMMs 1 7, 10Seventh pair of DIMMs 2 13, 16Eighth pair of DIMMs 2 21, 24Ninth pair of DIMMs 2 14, 17Tenth pair of DIMMs 2 20, 23Eleventh pair of DIMMs 2 15, 18Twelfth pair of DIMMs 2 19, 22Note: DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memory mirroredchannel mode when UDIMMs are installed in the server.Memory rank sparingThe memory rank sparing feature disables the failed memory from the systemconfiguration and activates a rank sparing DIMM to replace the failed active DIMM.You can enable either rank sparing memory or memory mirrored channel in theSetup utility (see “Starting the Setup utility” on page 109). When you use thememory rank sparing feature, consider the following information:Figure 1. Connectors on each memory channelChapter 2. Installing optional devices 63
