IBM 884015U Maintenance And Troubleshooting Manual page 38

v Each DIMM in a pair must be the same size and technology to ensure that the
v You can configure the server to use memory mirroring. Memory mirroring stores
v The server supports online-spare memory. This feature disables the failed
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xSeries 346 Types 8840 and 1880: Hardware Maintenance Manual and Troubleshooting Guide
Table 2. DIMM installation sequence
Pair DIMM connectors
1 1 and 2
2 3 and 4
3 5 and 6
4 7 and 8
server will operate properly.
data in two pairs of DIMMs simultaneously. Memory mirroring reduces the
amount of available memory. Enable memory mirroring through the
Configuration/Setup Utility program. See the User's Guide on the IBM xSeries
Documentation CD for details about enabling memory mirroring.
When using memory mirroring, you must install two pairs of DIMMs at a time.
The four DIMMs in each group must be identical. See Table 3 for the DIMM
connectors that are in each group.
Table 3. Memory mirroring DIMM installation sequence
Group DIMM connectors
1 1, 2, 3, and 4
2 5, 6, 7, and 8
memory from the system configuration and activates an online-spare memory
pair of DIMMs to replace the failed active DIMM pair. Online-spare memory
reduces the amount of available memory. Before you can enable this feature, you
must install one additional pair of DIMMs. The online-spare memory DIMM pair
must be the same speed, type, and the same size, or larger, than the active
DIMM pair.
Enable online-spare memory through the Configuration/Setup Utility program.
The BIOS code assigns the online-spare memory DIMM pair according to your
DIMM configuration. See the User's Guide on the IBM xSeries Documentation
CD for information about enabling online-spare memory. See Table 4 for the
online-spare memory DIMM connector assignments.
Table 4. Online-spare memory DIMM connector assignments
Active DIMM connectors
1 and 2
Online-spare memory DIMM connectors
3 and 4