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Memory rank sparing

The memory rank sparing feature disables the failed memory from the system configuration and activates a rank sparing DIMM to replace the failed active DIMM.

You can enable rank sparing memory in the Setup utility, select System Settings > Memory. For more information, see Using the Setup utility.

The maximum available memory is reduced when memory rank sparing mode is enabled.

The memory rank sparing mode requires an even number of DIMMs. If your server has an odd number of DIMMs installed, ensure that you disable the memory rank sparing mode from the Memory menu in Setup Utility. See Using the Setup utility for more information.
Note
After disabling the memory rank sparing mode, if a message prompts that the memory configuration is not valid, restart the integrated management module II (IMM2.1). Alternatively, you can turn off the server, disconnect it from and then reconnect it to ac power, and then turn on the server again.
The following diagram lists the DIMM connectors on each memory channel.
Figure 1. Connectors on each memory channel
Connectors on each memory channel
Follow the installation sequence for rank sparing mode:
  • Install at least one quad-rank DIMM in a channel.
  • Install at least two single-rank or dual-rank DIMMs in a channel.
  • Install even number of DIMMs for single-rank or dual-rank.
Table 1. Memory rank sparing mode DIMM population sequence when only quad-rank RDIMMs are installed
Number of installed microprocessorDIMM connector population sequence on the system board
One microprocessor installed7, 8-> 1, 2-> 5, 6-> 3, 4
Two microprocessors installed7, 8-> 9, 10-> 1, 2-> 15, 16-> 5, 6-> 11, 12-> 3, 4-> 13, 14