Memory Mirroring - IBM System x3650 M4 BD Type 5466 Installation And Service Manual

Table 8. DIMM connectors on each memory channel
Number of installed
microprocessors
Microprocessor 2

Memory mirroring

Memory-mirroring mode replicates and stores data on two pairs of DIMMs within
two channels simultaneously.
About this task
Memory-mirroring mode replicates and stores data on two pairs of DIMMs within
two channels simultaneously. If a failure occurs, the memory controller switches
from the primary pair of memory DIMMs to the backup pair of DIMMs. You must
enable memory mirroring through the Setup utility. For details about enabling
memory mirroring, see "Using the Setup utility" on page 91. When you use the
memory mirroring feature, consider the following information:
v DIMMs must be installed in pairs. The DIMMs in each pair must be the same
size and type.
v The maximum available memory is reduced to one third of the installed
memory when memory mirroring is enabled. For example, if you install 96 GB
of memory, only 32 GB of addressable memory is available when you use
memory mirroring.
v Channel 1 DIMM connectors 1, 2, 7, and 8 are not used in memory-mirroring
mode.
The following table lists the installation sequence for installing DIMMs in
memory-mirroring mode.
Table 9. DIMM population sequence (memory-mirroring mode)
Number of installed microprocessors
1
2
When you install or remove DIMMs, the server configuration information changes.
When you restart the server, the system displays a message that indicates that the
memory configuration has changed.
Memory channel
Channel 1
Channel 2
Channel 3
Channel 4
DIMM connector population sequence
8, 6
1, 3
7, 5
2, 4
8, 6, 16, 14
1, 3, 9, 11
7, 5, 15, 13
2, 4, 10, 12
Chapter 2. Installing optional devices
DIMM connectors
15, 16
13, 14
9, 10
11, 12
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