When you use memory mirroring, you must install two pairs of DIMMs at a time.
The four DIMMs in each group must be identical. See Table 4 for the DIMM
connectors that are in each group.
Table 4. Memory mirroring DIMM installation sequence
Group DIMM connectors
1 1, 4, 7, and 10
2 2, 5, 8, and 11
3 3, 6, 9, and 12
Table 5. Memory mirroring DIMM functions
Group Active DIMMs Mirroring DIMMs
1 1, 4 7, 10
2 2, 5 8, 11
3 3, 6 9, 12
Online-spare memory
The server supports online-spare memory. This feature disables the failed memory
from the system configuration and activates an online-spare 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 up to two additional pairs of DIMMs. The
online-spare DIMM pairs must be the same speed, type, and the same size as, or
larger than, the largest active DIMM pairs.
Enable online-spare memory through the Configuration/Setup Utility program. The
BIOS code assigns the online-spare DIMM pairs according to your DIMM
configuration. Online-sparing is enabled on a memory branch basis; the BIOS code
does not enable online-sparing on a branch that cannot support online-sparing. See
the illustration on page 61 for the memory branch structure. DIMM ranks are
online-spared if the DIMMs are installed according to the rules in Table 6 on page
64 or Table 7 on page 64.
Note:
POST gives a warning message when online-sparing cannot be enabled on
both branches. However, no warning message is given when online-sparing is
enabled on one branch and disabled on the other.
Online-spare configurations are supported for each branch. See Table 6 on page 64
and Table 7 on page 64 for the online-spare DIMM connector assignments.
Important: Table 6 on page 64 shows the basic DIMM online-spare scheme. If the
BIOS code level is version 1.04 or later, you can install the DIMMs according to the
alternative scheme, shown in Table 7 on page 64, instead.
Chapter 2. Installing optional devices 63
