IBM System x3650 M4 Type 7915, Installation And User Manual

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Memory mirrored channel
Memory mirrored channel 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. To
enable memory mirrored channel through the Setup utility, select
System Settings
→
Memory . For more information, see “Using the Setup utility” on page 145. When
you use the memory mirrored channel feature, consider the following information:
v
When you use memory mirrored channel, you must install a pair of DIMMs at a
time. The two DIMMs in each pair must be identical in size, type, and rank
(single, dual, or quad), and organization, but not in speed. The channels run at
the speed of the slowest DIMM in any of the channels.
v The maximum available memory is reduced to half of the installed memory when
memory mirrored channel is enabled. For example, if you install 64 GB of
memory using RDIMMs, only 32 GB of addressable memory is available when
you use memory mirrored channel.
v
For UDIMMs, DIMM connectors 3, 6, 7, and 10 for microprocessor 1 and DIMM
connectors 15, 18, 19, and 22 for microprocessor 2 are not used in memory
mirrored channel mode.
The following diagram lists the DIMM connectors on each memory channel.
The following table shows the installation sequence for installing DIMMs in
memory-mirroring mode:
Table 9. Memory mirrored channel mode DIMM population sequence
Number of DIMMs
Number of installed
microprocessor
DIMM connector
First pair of DIMMs 1 1, 4
Second pair of DIMMs 1 9, 12
Third pair of DIMMs 1 2, 5
Fourth pair of DIMMs 1 8, 11
Fifth pair of DIMMs 1 3, 6
Sixth pair of DIMMs 1 7, 10
Seventh pair of DIMMs 2 13, 16
Eighth pair of DIMMs 2 21, 24
Ninth pair of DIMMs 2 14, 17
Tenth pair of DIMMs 2 20, 23
Eleventh pair of DIMMs 2 15, 18
Twelfth pair of DIMMs 2 19, 22
Note: DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memory mirrored
channel mode when UDIMMs are installed in the server.
DIMM 3 DIMM 9 DIMM 6 DIMM 12 DIMM 2 DIMM 8 DIMM 5 DIMM 11 DIMM 1 DIMM 7 DIMM 4 DIMM 10
CH1 Ch2 CH0 Ch3
Microprocessor 1
CPU1
DIMM 15 DIMM 21 DIMM 18 DIMM 24 DIMM 14 DIMM 20 DIMM 17 DIMM 23 DIMM 13 DIMM 19 DIMM 16 DIMM 22
CH1 Ch2 CH0 Ch3
Microprocessor 2
CPU2
Figure 1. Memory channel interface layout
Chapter 2. Installing optional devices
111