– 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, see the section about configuring the server in
the User’s Guide on the IBM System x Documentation CD. 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.
- When using online-spare memory the two memory branches operate
independently of each other. You can enable online-spare memory for one
or both branches.
- Online-spare memory reduces the amount of available memory.
- The BIOS code assigns the online-spare DIMM pairs according to your
DIMM configuration.
- Online-spare memory works by copying information from a failed DIMM
rank to another good DIMM rank within the same memory branch.
- Online-spare memory can not copy information from one branch to the
other.
Chapter 2. Installing optional devices 13
