Intel SR9000MK4U - Manual (Page 48)

26 Intel ® Server System SR9000MK4U Product Guide
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.
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.
Table 14. Memory Operational Modes
Memory
Operational
Mode
Description
Number of
MMR
Connected
to One NDC
BIOS Set-Up
of Mirror
Mode
Redundancy
and Hot-
swap
Support
Single One MMR is connected to
an NDC. No redundancy.
Throughput of data
transfer is half that of
Double mode.
1 Disabled or
Enabled
No
Double Two MMRs are connected
to an NDC. No
redundancy. Throughput
of data transfer is double
that of Single mode.
2 Disabled No
Mirror Two MMRs are connected
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.
2 Enabled Yes