310 IBM eX5 Implementation Guide7.3.3 Memory fault toleranceFor servers with high availability requirements, using the memory mirroring or memorysparing configuration allows the server to continue to function normally in the rare event of amemory failure. See 2.3.6, “Reliability, availability, and serviceability (RAS) features” onpage 28 for an explanation of the memory mirroring and memory sparing functions.Note, however, that considering that memory is like a solid-state device, it is unlikely that aDIMM failure will occur outside of the first 90 days of operation. Statistically, there is a higherrisk for failure with power supplies, copper network adapters, storage devices, or processors.High availability is almost always a desired goal, but for true high availability, consider acluster of host computers using common storage that allows virtual servers to be defined andmoved from one host server to another host server.If high availability is the most important aspect of your server (with cost and performance assecondary concerns), enable memory mirroring or memory sparing.Use the following steps to establish memory mirroring or memory sparing:1. Boot the server into F1-Setup.2. From the System Configuration panel, select System Settings Memory (Figure 7-8).Figure 7-8 Memory configuration panel in F1-SetupFigure 7-8 shows the Memory configuration panel with selections for performing memorysparing or memory mirroring, but not both at the same time. Select the desired option andreboot the server. If your memory population order does not support the requested option, theserver will report a memory configuration error during the next reboot.See 4.8.2, “x3690 X5 memory population order” on page 133 for the correct memorypopulation order to support memory mirroring or sparing.
