IBM System x3400 Type 7975 Installation Manual page 31

For more information on the Configuration/Setup Utility program, see the
User's Guide. When you use memory mirroring, consider the following
information:
- The maximum available memory is reduced to 16 GB, instead of the 32 GB
available in non-mirroring mode.
- The minimum memory configuration is four identical DIMMs. You must
install identical pairs of fully buffered, dual-inline memory modules (DIMMs)
in all four DIMM connectors (same size, type, speed, and technology).
These DIMMs must span across both branches and all four channels. For
example, when you install the first four DIMMs, you must install two DIMMs
in branch 0 (one in channel 0 and one in channel 1) and two DIMMs in
branch 1 (one in channel 2 and one in channel 3). See Table 3 for the
DIMM installation sequence.
- When you upgrade the server to eight DIMMs, the DIMMs that are next to
each other (for example, DIMM connector 1 and DIMM connector 4) within
the channels of a branch must be identical in size, type, speed, and
technology. However, the DIMMs in the connectors above or below each
other within the channels of a branch do not have to be identical to each
other (for example, the DIMMs in DIMM connector 1 and DIMM connector
2).
- Both branches operate in dual-channel mode.
The following table shows the DIMM configuration upgrade sequence for
operating in mirroring mode.
Table 3. DIMM upgrade configuration sequence in mirroring mode
Number of DIMMs
4
8
Note: DIMM connectors 3, 6, 9, and 12 are not functional in this server. Do not install
DIMMs in these connectors.
– Online-spare memory disables a failed rank pair of DIMMs from the system
configuration and activates an online-spare rank pair of DIMMs to replace the
failed rank pair of DIMMs. For an online-spare pair of DIMMs to be activated,
you must enable this feature and have installed an additional rank pair of
DIMMs of the same speed, type, size (or larger), and technology as the failed
pair of DIMMs. You must enable the feature through the Configuration/Setup
Utility program. To enable online-spare memory in the Configuration/Setup
Utility program, select Devices and I/O Ports → Advanced Chipset Control →
Memory Branch Mode. Use the arrow keys to change the setting for Branch
0 Rank Sparing or Branch 1 Rank Sparing to Enabled ; then, save your
changes. For more information on the Configuration/Setup Utility program, see
the User's Guide. When you use online-spare memory, you must consider the
following information:
- You cannot enable online-spare memory while the server is operating in
mirroring mode.
- The minimum memory configuration is two single-rank DIMMs installed in
branch 0, DIMM connector 1 (in channel 0) and connector 4 (in channel 1);
however, online-sparing is not supported with this configuration.
- To support online-sparing in branch 0, you must add a second pair of
DIMMs. The spare pair of DIMMs can be single-rank or double-rank and
must be the same speed, type, size (or larger), and technology as the
failed pair of DIMMs. The spare pair must be installed in branch 0, DIMM
DIMM connectors
1, 4, 7, 10
1, 4, 7, 10, 2, 5, 8, 11
Chapter 2. Installing options
17