Lenovo 6446 - Manual (Page 28)

switches from the active pair to the mirroring pair. Memory mirroring reduces the
amount of available memory. Enable memory mirroring through the
Configuration/Setup Utility program. See the section about using the
Configuration/Setup Utility program in the User Guide on the ThinkServer
Documentation DVD for details about enabling memory mirroring.
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 3 for the DIMM
connectors that are in each group.
Table 3. 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 4. 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 11 for the memory branch structure. DIMM ranks are
online-spared if the DIMMs are installed according to the rules in Table 5 on page
15 or Table 6 on page 15.
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 5 on page 15
and Table 6 on page 15 for the online-spare DIMM connector assignments.
Important: Table 5 on page 15 shows the default DIMM online-spare scheme. If the
BIOS code level is version 1.04 or later, you can install the DIMMs according to the
scheme shown in Table 6 on page 15 instead.
14 ThinkServer RD120 Types 6444, 6445, 6446, and 6447: Installation Guide