Intel SR9000MK4U manual Memory Operational Modes, Memory Number Bios Set-Up Redundancy, Hot

Three memory modes are available. The memory mode is selected depending on the number of memory boxes that are connected to one NDC chip, and whether the BIOS is configured for mirror mode. See the following table for information.

Table 14. Memory Operational Modes

Memory		Number of	BIOS Set-Up	Redundancy
		MMR		and Hot-
Operational	Description		of Mirror
		Connected		swap
Mode			Mode
		to One NDC		Support
Single	One MMR is connected to	1	Disabled or	No
	an NDC. No redundancy.		Enabled
	Throughput of data
	transfer is half that of
	Double mode.
Double	Two MMRs are connected	2	Disabled	No
	to an NDC. No
	redundancy. Throughput
	of data transfer is double
	that of Single mode.
Mirror	Two MMRs are connected	2	Enabled	Yes
	to an NDC and the same
	data is stored in these two
	MMR. Two MMRs are
	running like a mirror of
	each other and provide
	redundancy. Throughput
	of data transfer is half that
	of Double mode.

The following figures show the installation order and upgrade path for DIMMs, and the applicable mode for each configuration. In these figures, solid lines indicate installed memory boxes; dotted lines indicated locations of empty memory box sockets. Black boxes indicate installed DIMMs.

The first set of figures (1-A, 2-A, 3-A, 4-A) represent configurations in which four DIMMs are installed in each installed memory box. The paths to the right of the figures marked 'W', 'X', 'Y', and 'Z' show the upgrade to fully populated memory boxes (eight DIMMs in each memory box). These fully populated configurations are shown in the second set of figures (1-B, 2-B, 3-B, 4-B).

For example, configuration 1-A has only one MMR with four DIMMs installed, so only single mode is applicable. This configuration can be connected to three paths for upgrade, that is, to 2-A, 3-A. and 1-B.

In the paths to 2-A and 3-A, another memory box is needed. 2-A has a higher memory bandwidth than 3-A, because 2-A can use two NDC chips effectively. In 3-A, processors connected to the NDC linked to the MC with DIMMs installed can access all of the system memory with the shortest access time. Therefore, in some specialized situations, 3- A has a performance advantage to 2-A, such as in a two-socket installation.

26 Intel® Server System SR9000MK4U Product Guide