Memory Mirrored Channel - Lenovo x3550 M4 Installation And Service Manual

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 102. 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
v The maximum available memory is reduced to half of the installed memory
v For UDIMMs, DIMM connectors 3, 6, 7, and 10 for microprocessor 1 and DIMM
The following diagram lists the DIMM connectors on each memory channel.
Figure 36. Connectors on each memory channel
The following table shows the installation sequence for memory mirrored channel
mode:
52
System x3550 M4 Type 7914: Installation and Service Guide
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.
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.
connectors 15, 18, 19, and 22 for microprocessor 2 are not used in memory
mirrored channel mode.
Table 7. Memory mirrored channel mode DIMM population sequence
Number of DIMMs
First pair of DIMMs
Second pair of DIMMs
Third pair of DIMMs
Fourth pair of DIMMs
Fifth pair of DIMMs
Sixth pair of DIMMs
Seventh pair of DIMMs
Eighth pair of DIMMs
Ninth pair of DIMMs
Tenth pair of DIMMs
Eleventh pair of DIMMs
Twelfth pair of DIMMs
Number of installed
microprocessor
1
1
1
1
1
1
2
2
2
2
2
2
DIMM connector
1, 4
9, 12
2, 5
8, 11
3, 6
7, 10
13, 16
21, 24
14, 17
20, 23
15, 18
19, 22