IBM System x3650 M4 BD Type 5466, Installation And Service Manual

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Rank sparing
Sparing enables a failing rank to be replaced by ranks installed in an unoccupied
space. An unused spare rank on the channel can be used to copy the contents of a
failing rank on that channel.
About this task
When you use the memory mirroring feature, consider the following information:
v
In rank sparing mode, one rank of a DIMM in each populated channel is
reserved as spare memory. The spare rank is not available as active memory.
When the active rank memory fails, its content is copied to the spare rank
memory which becomes active. The spare rank must have identical or larger
memory capacity than all the other ranks on the same channel.
v
DIMMs must be installed in sets of three. The DIMMs in each set must be the
same size and type.
v
The following table lists the DIMM installation sequence for rank sparing mode
when one or two microprocessors is installed in the server:
The following table shows the installation sequence for installing DIMMs for each
microprocessor in memory online-spare mode:
Table 10. DIMM population sequence (rank sparing mode)
Number of installed
microprocessors
DIMM connector population sequence
1 8, 7
1, 2
6, 5
3, 4
2 8, 7, 16, 15
6, 5
14, 13
1,2
9, 10
3, 4
11, 12
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System x3650 M4 BD Type 5466: Installation and Service Guide