Memory mirroring

Memory-mirroring replicates and stores data on DIMMs across all four memory channels for the compute book and DDR3 or DDR4 channels simultaneously. If a failure occurs, the memory controller switches from the DIMMs on the primary channels to the DIMMs on the backup channels. To enable memory mirroring through the Setup utility, select System Settings → Memory → Memory Mode. For more information, see Using the Setup utility. For more information and notes about installing DIMMs, see Installing a memory module. For more information and the DIMM population sequence for memory mirroring, see Memory mirroring in independent memory mode and Memory mirroring in lockstep mode.

Memory mirroring is supported in independent mode and lockstep mode.

When you use the memory mirroring feature, consider the following information:

• The server supports single-socket memory mirroring. The compute book memory channel 0 mirrors memory channel 1, and memory channel 2 mirrors memory channel 3. This mirroring provides redundancy in memory but reduces the total memory capacity in half.
• DIMMs must be installed in pairs for each compute book when using the memory mirroring feature.
• The DIMM population must be identical (size, organization, etc.) for memory channel 0 and memory channel 1, and identical for memory channel 2 and memory channel 3.
• Memory mirroring reduces the maximum available memory by half of the installed memory. For example, if the server has 64 GB of installed memory, only 32 GB of addressable memory is available when memory mirroring is enabled.