Online-spare memoryThe memory online-spare feature disables the failed memory from the systemconfiguration and activates an online-spare DIMM to replace the failed activeDIMM.You can enable either online-spare memory or memory mirroring in the Setuputility (see “Using the Setup utility” on page 112). When you use the memoryonline-spare feature, 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 threeDIMMs per microprocessor at a time. The first DIMM must be in channel 0, thesecond DIMM in channel 1, and the third DIMM in channel 2. The DIMMs mustbe identical in size, type, rank, and organization, but not in speed. The channelsrun at the speed of the slowest DIMM in any of the channels.v The maximum available memory is reduced to 2/3 of the installed memorywhen memory online-spare mode is enabled. For example, if you install 72 GBof memory using RDIMMs, only 48 GB of addressable memory is availablewhen you use memory online-spare.The following table shows the installation sequence for installing DIMMs for eachmicroprocessor in memory online-spare mode:Table 13. Memory online-spare mode DIMM populationsequenceInstalledMicroprocessor DIMM connectorMicroprocessor 1 3, 6, 93, 6, 9, 2, 5, 83, 6, 9, 2, 5, 8, 1, 4, 7Microprocessor 2 12, 15, 18,12, 15, 18, 11, 14, 17,12, 15, 18, 11, 14, 17, 10, 13, 16Installing a DIMMUse this information to install a DIMM.About this taskTo install a DIMM, complete the following steps:Procedure1. Read the safety information that begins on “Safety” on page v and “Installationguidelines” on page 43.2. Turn off the server and peripheral devices and disconnect the power cords andall external cables, if necessary.3. Remove the cover (see “Removing the cover” on page 51).4. Open the retaining clip on each end of the DIMM connector.60 IBM System x3550 M3 Type 4254 and 7944: Installation and User's Guide
