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 . 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.
- 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.
Figure 1. Connectors on each memory channel
The following table shows the installation sequence for memory mirrored channel mode:
| 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 |
Table 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.
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