IBM System x3300 M4 Installation And Service Manual page 83

– DIMMs must be installed in sets of three. The DIMMs in each set must be the
same size and type.
– The following table lists the DIMM installation sequence for rank sparing
mode when one or two microprocessors is installed in the server:
Table 10. DIMM population sequence (rank sparing mode)
Number of installed
microprocessors
1
2
v Memory-mirroring mode: When you use the memory mirroring feature,
consider the following information:
– Memory-mirroring mode replicates and stores data on two pairs of DIMMs
simultaneously. If a failure occurs, the memory controller switches from the
primary pair of memory DIMMs to the backup pair of DIMMs. This
mirroring provides redundancy in memory but reduces the total memory
capacity to one third. Channel 1 DIMM connectors 3, 4, 9, and 10 are not used
in memory-mirroring mode. To enable memory mirroring through the Setup
utility, select System Settings → Memory. For more information, see "Using
the Setup utility" on page 115.
– DIMMs must be installed in pairs. The DIMMs in each pair must be the same
size and type.
– 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.
– The following table lists the DIMM installation sequence for
memory-mirroring mode when one or two microprocessors is installed in the
server:
Table 11. DIMM population sequence (memory-mirroring mode)
Number of installed
microprocessors
1
2
v 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.
DIMM connector population sequence
1, 3, 5
2, 4, 6
1, 3, 5
7, 9, 11
2, 4, 6
8, 10, 12
DIMM connector population sequence
3, 5
4, 6
3, 5
9, 11
4, 6
10, 12
Chapter 2. Installing optional devices
65