Memory Rank Sparing - IBM System x3500 Installation And User Manual

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.

Memory 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. You can enable rank sparing memory in the Setup
utility, select System Settings → Memory. For more information, see "Using the
Setup utility" on page 120.
The following diagram lists the DIMM connectors on each memory channel.
Figure 14. Connectors on each memory channel
You can install DIMMs for the microprocessor 2 once the microprocessor 2 is
installed. You do not need to wait until all of the DIMM connectors for
microprocessor 1 are filled. The following table shows the installation sequence for
memory rank sparing mode:
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IBM System x3500 M4 Type 7383: Installation and User's Guide
Table 7. Memory mirrored channel mode DIMM population sequence (continued)
Number 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
Note: DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memory mirrored
mode when UDIMMs are installed in the server.
Table 8. Memory rank sparing 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
Number of installed
microprocessor
2
2
2
2
2
2
Number of installed
microprocessor
1
1
1
1
1
1
2
DIMM connector
13, 16
21, 24
14, 17
20, 23
19, 22
15, 18
DIMM connector
1, 2
4, 5
8, 9
11, 12
7, 10
3, 6
13, 14