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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.
Note
After disabling the memory rank sparing mode, if a message prompts that the memory configuration is not valid, restart the IMM2. 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.
Table 1. Memory rank sparing mode DIMM population sequence when only quad-rank RDIMMs are installed
Number of installed microprocessorsDIMM connector population sequence on the system board
One1, 4, 9, 12, 2, 5, 8, 11
Two1, 13, 4, 16, 9, 21, 12, 24, 2, 14, 5, 17, 8, 20, 11, 23
Table 2. Memory rank sparing mode DIMM population sequence when single/dual/quad rank DIMMs are installed and the total number of DIMMs is even.

DIMMsNumber of installed microprocessorsDIMM connector population sequence on the system board
One Microprocessor
1st set11, 2
2nd set14, 5
3rd set18, 9
4th set111, 12
5th set13, 6
6th set17, 10
Two Microprocessors
1st set21, 2
2nd set213, 14
3rd set24, 5
4th set216, 17
5th set28, 9
6th set220, 21
7th set211, 12
8th set223, 24
9th set23, 6
10th set215, 18
11th set27, 10
12th set219, 22
Table 3. Memory rank sparing mode DIMM population sequence when single/dual/quad rank DIMMs are installed and the total number of DIMMs is odd.

DIMMsNumber of installed microprocessorsDIMM connector population sequence on the system board
One Microprocessor
1st set11, 2, 3
2nd set14, 5
3rd set18, 9
4th set111, 12
5th set16, 7
Two Microprocessors
1st set21, 2, 3
2nd set213, 14
3rd set24, 5
4th set216, 17
5th set28, 9
6th set220, 21
7th set211, 12
8th set223, 24
9th set26, 7
10th set218, 19
11th set210, 22