Memory sparing

This section contains information pertaining to the memory-sparing mode of operation.

In the memory-sparing mode, one rank is held in reserve as a spare of the other ranks in the same channel. The server supports memory sparing. Memory sparing reserves memory capacity for failover in the event of a DIMM failure, and the reserved capacity is subtracted from the total available memory. Memory sparing provides less redundancy than memory mirroring does. If a predetermined threshold of correctable errors is reached, the contents of the failing DIMM are copied to the spare memory, and the failing DIMM or rank is disabled. To enable memory sparing through the Setup utility, select System Settings → Memory → Memory Mode.

When you use the memory sparing mode, consider the following information:

• When single-rank or dual-rank DIMMs are used, at least three DIMMs must be installed to support memory sparing.
• Each memory channel supports three DIMMs. The third DIMM in each channel is the sparing DIMM for all of the DIMMs in the channel.
• When quad-rank DIMMs are used, one of the ranks in the DIMM itself is used for sparing.
• The server does not support the mixing of single and dual-rank registered DIMMs (RDIMM) with quad-rank load-reduced DIMMs (LR-DIMM).

The following table shows the DIMM population sequence for the memory-sparing mode.

Note

The server does not support a configuration of three microprocessors. The server supports one, two, or four microprocessors only.

Table 1. DIMM population sequence for memory sparing mode.

Four column table with headers documenting DIMM population sequence for memory sparing mode. Three rows span across all columns.

DIMMs	Number of microprocessors	DIMM connector population sequence on the system board	DIMM connector population sequence on the optional microprocessor and memory expansion tray
One microprocessor
1st set	1	1, 2, 3
2nd set	1	10, 11, 12
3rd set	1	4, 5, 6
4th set	1	7, 8, 9
Two microprocessors
1st set	2	1, 2, 3, 13, 14, 15
2nd set	2	10, 11, 12, 22, 23, 24
3rd set	2	4, 5, 6, 16, 17, 18
4th set	2	7, 8, 9, 19, 20, 21
Four microprocessors
1st set	4	1, 2, 3, 13, 14, 15	25, 26, 27, 37, 38, 39
2nd set	4	10, 11, 12, 22, 23, 24	34, 35, 36, 46, 47, 48
3rd set	4	4, 5, 6, 16, 17, 18	28, 29, 30, 40, 41, 42
4th set	4	7, 8, 9, 19, 20, 21	31, 32, 33, 43, 44, 45

• The server supports a maximum of 24 DIMMs (single-rank, dual-rank, or quad-rank) on the base system board. If you mix single-rank, dual-rank or quad-rank DIMMs in the server, quad-rank DIMMs must be installed first.
  Note

  To determine the type of DIMM, see the label on the DIMM. The information on the label is in the format xxxxx nRxxx PC3-xxxxx-xx-xx-xxx. The numeral in the sixth numerical position indicates whether the DIMM is single-rank (n=1) or dual-rank (n=2).
• The following tables list the supported combinations of single-rank and dual-rank standard RDIMMs and quad-rank LR-DIMMs that you can install in the server.
  Note

  In the following table, the location of the DIMMs in the memory channels are defined as follows:

  • Near DIMM: The DIMM in the memory channel that is the closest to the microprocessor.
  • Middle DIMM: The middle DIMM in the memory channel.
  • Far DIMM: The DIMM in the memory channel that is the farthest from the microprocessor.
  The following table lists the supported combinations of ranked registered DIMMs (RDIMMs) that you can install in the server.

  Note

  The server does not support the mixing of single and dual-rank RDIMMs with quad-rank LR-DIMMs.

  Table 2. Supported combinations of ranked RDIMMs per memory channel.

  Four column table with headers documenting the supported combinations of ranked registered DIMMs.

  Configuration	DIMM 1 (far DIMM)	DIMM 2 (middle DIMM)	DIMM 3 (near DIMM)
  1	Single-rank	Empty	Empty
  2	Dual-rank	Empty	Empty
  3	Single-rank	Single-rank	Empty
  4	Dual-rank	Single-rank	Empty
  5	Dual-rank	Dual-rank	Empty
  6	Single-rank	Single-rank	Single-rank
  7	Dual-rank	Single-rank	Single-rank
  8	Dual-rank	Dual-rank	Single-rank
  9	Dual-rank	Dual-rank	Dual-rank

  The following table lists the supported combinations of ranked LR-DIMMs that you can install in the server.

  Note

  The server does not support the mixing of single and dual-rank RDIMMs with quad-rank LR-DIMMs in the same server.

  Table 3. Supported combinations of ranked LR-DIMMs per memory channel.

  Four column table with headers documenting the supported combinations of ranked LR-DIMMs.

  Configuration	DIMM 1 (far DIMM)	DIMM 2 (middle DIMM)	DIMM 3 (near DIMM)
  1	Quad-rank	Empty	Empty
  2	Quad-rank	Quad-rank	Empty
  3	Quad-rank	Quad-rank	Quad-rank

• The following table lists the memory speed based on the type of ranked DIMM and the voltage at which the DIMM runs.

  Table 4. Memory speeds and configurations based on ranked DIMM type and voltage.

  Eight column table with five headers documenting the memory speed based on the ranked DIMM type and voltage. The second row spans across the first two columns.

  DIMM rank, type, and technology	DIMM capacity	1 DIMM per channel		2 DIMMs per channel		3 DIMMs per channel
  		1.35 V	1.50 V	1.35 V	1.50 V	1.35 V	1.50 V
  Single-rank x4 RDIMM - 2 Gb (1600 MHz)	4 GB	1600	1600	1600	1600	1066	1333
  Single-rank x4 RDIMM - 2 Gb (1866 MHz)	4 GB		1866		1866		1333
  Single-rank x4 RDIMM - 4 Gb (1600 MHz)	8GB	1600	1600	1600	1600	1066	1333
  Single-rank x4 RDIMM - 4 Gb (1866 MHz)	8GB		1866		1866		1333
  Dual-rank x4 RDIMM - 4 Gb (1600 MHz)	16GB	1600	1600	1600	1600	1066	1333
  Dual-rank x4 RDIMM - 4 Gb (1866 MHz)	16GB		1866		1866		1333
  Quad-rank x4 LRDIMM - 4Gb (1600 MHz)	32 GB	1600	1600	1600	1600	1333	1333
  Quad-rank x4 LRDIMM - 4Gb (1866 MHz)	32GB		1866		1866		1333