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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.

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. When you use the memory mirrored channel feature, consider the following information:
  • 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.
  • 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.
The following diagram lists the DIMM connectors on each memory channel.
Figure 1. Connectors on each memory channel
Connectors on each memory channel
Note
You can install DIMMs for microprocessor 2 as soon as you install microprocessor 2; you do not have to wait until all of the DIMM connectors for microprocessor 1 are filled.

The following table shows the installation sequence for memory mirrored mode:

Table 1. Memory mirrored channel mode DIMM population sequence.

Three column table for documenting the number of DIMMs, number of installed microprocessor, and DIMM connector.

Number of DIMMsNumber of installed microprocessorDIMM connector
First pair of DIMMs11, 4
Second pair of DIMMs19, 12
Third pair of DIMMs12, 5
Fourth pair of DIMMs18, 11
Fifth pair of DIMMs17, 10
Sixth pair of DIMMs13, 6
First pair of DIMMs21, 4
Second pair of DIMMs213, 16
Third pair of DIMMs29, 12
Fourth pair of DIMMs221, 24
Fifth pair of DIMMs22, 5
Sixth pair of DIMMs214, 17
Seventh pair of DIMMs28, 11
Eighth pair of DIMMs220, 23
Ninth pair of DIMMs219, 22
Tenth pair of DIMMs27, 10
Eleventh pair of DIMMs215, 18
Twelfth pair of DIMMs23, 6

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.