Table 7. Memory mirrored channel mode DIMM population sequence (continued)Number of DIMMsNumber of installedmicroprocessor DIMM connectorTable note: DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memorymirrored channel 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 activeDIMM.You can enable rank sparing memory in the Setup utility, select System Settings >Memory. For more information, see “Using the Setup utility” on page 106.The maximum available memory is reduced when memory rank sparing mode isenabled.The following diagram lists the DIMM connectors on each memory channel.Follow the installation sequence for rank sparing mode:v Install at least one quad-rank DIMM in a channel.v Install at least two single-rank or dual-rank DIMMs in a channel.Table 8. Memory rank sparing mode DIMM population sequenceNumber of DIMMsNumber of installedmicroprocessor DIMM connectorFirst pair of DIMMs 1 1, 2Second pair of DIMMs 1 4, 5Third pair of DIMMs 1 8, 9Fourth pair of DIMMs 1 11, 12Fifth pair of DIMMs 1 7, 10Sixth pair of DIMMs 1 3, 6Seventh pair of DIMMs 2 13, 14Eighth pair of DIMMs 2 16, 17Ninth pair of DIMMs 2 20, 21Tenth pair of DIMMs 2 23, 24Eleventh pair of DIMMs 2 19, 22Twelfth pair of DIMMs 2 15, 18Table note: DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memory ranksparing mode when UDIMMs are installed in the server.Figure 37. Connectors on each memory channel54 IBM System x3550 M4 Type 7914: Installation and Service Guide
