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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 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.
Table 1. Memory rank sparing mode DIMM population sequence.

The memory rank sparing mode DIMM population sequence table. There are three columns. This first column heading is number of DIMMs. The second column heading is number of installed microprocessor. The third column heading is DIMM connector.

Number of DIMMsNumber of installed microprocessorDIMM connector
First pair of DIMMs11, 2
Second pair of DIMMs14, 5
Third pair of DIMMs18, 9
Fourth pair of DIMMs111, 12
Fifth pair of DIMMs17, 10
Sixth pair of DIMMs13, 6
Seventh pair of DIMMs213, 14
Eighth pair of DIMMs216, 17
Ninth pair of DIMMs220, 21
Tenth pair of DIMMs223, 24
Eleventh pair of DIMMs219, 22
Twelfth pair of DIMMs215, 18
Note
DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memory rank sparing mode when UDIMMs are installed in the server.