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IBM System x3850 X5 and x3950 X5 Types 7145, 7146, 7143, and 7191: Installation and User's Guide
– Memory mirroring reduces the available memory by half. For example, if the
server has 64 GB of installed memory, only 32 GB of addressable memory is
available when memory mirroring is enabled.
To enable memory mirroring, you must install DIMMs in sets of four, one pair in
each memory card. All DIMMs in each set must be the same size and type.
Memory cards 1 and 2 mirror each other, cards 3 and 4 mirror each other,
memory cards 5 and 6 mirror each other, and cards 7 and 8 mirror each other.
Install DIMMs in the sequence shown in the following table.
Table 9. Memory-card installation sequence for memory-mirroring configuration
DIMM quad installation
order
First
Second
Third
Fourth
Fifth
Sixth
Seventh
Eighth
Ninth
Tenth
Eleventh
Twelfth
Thirteenth
Fourteenth
Fifteenth
Sixteenth
Memory card
1
2
7
8
3
4
5
6
1
2
7
8
3
4
5
6
1
2
7
8
3
4
5
6
1
2
7
8
3
4
5
6
Connector numbers
1 and 8
1 and 8
1 and 8
1 and 8
1 and 8
1 and 8
1 and 8
1 and 8
3 and 6
3 and 6
3 and 6
3 and 6
3 and 6
3 and 6
3 and 6
3 and 6
2 and 7
2 and 7
2 and 7
2 and 7
2 and 7
2 and 7
2 and 7
2 and 7
4 and 5
4 and 5
4 and 5
4 and 5
4 and 5
4 and 5
4 and 5
4 and 5