HP DL380 - Manual (Page 32)

FBDIMM slot 1A.
FBDIMMs must be installed in sequential order, beginning with bank A.
In Advanced ECC mode, FBDIMMs must be populated as specified in the following table:
Configuration
Bank A
1A and 3A
Bank B
5B and 7B
Bank C
2C and 4C
Bank D
6D and 8D
1 X - - -
2 X X - -
3 X X X -
4 X X X X
Online spare memory configuration
Online spare memory provides protection against degrading FBDIMMs by reducing the likelihood of uncorrectable memory errors.
An understanding of single-rank and dual-rank FBDIMMs is required to understand memory usage in online spare mode. FBDIMMs
can either be single-rank or dual-rank. Certain FBDIMM configuration requirements are based on these classifications. A dual-rank
FBDIMM is similar to having two separate FBDIMMs, or ranks, on the same module. Although only a single FBDIMM module, a dual-
rank FBDIMM acts as two separate FBDIMMs. The purpose of dual-rank FBDIMMs is to provide the largest capacity FBDIMM for the
current DRAM technology. If the current DRAM technology allows for 2-GB single-rank FBDIMMs, a dual-rank FBDIMM using the
same technology would be 4-GB.
In online spare mode, a single rank of memory acts as the spare memory. For single-rank FBDIMMs, the entire FBDIMM acts as the
spare memory. For a dual-rank FBDIMM, only half of the FBDIMM acts as the spare memory while the other half is available for
operating system and application usage.
If one of the non-spare FBDIMMs receives correctable memory errors at a higher rate than a specific threshold, the server
automatically copies the memory contents of the degraded rank to the online spare rank. The server then deactivates the failing rank
and automatically switches over to the online spare. Because FBDIMMs that experience a high rate of correctable memory errors
have a higher probability of receiving an uncorrectable memory error, this effectively reduces the likelihood of uncorrectable memory
errors that would result in server downtime.
Online spare is performed per branch of the memory controller. For a server populating both branches, two ranks are utilized for
online spare memory. One branch can have a fail over to the associated online spare while the other branch is still protected.
Each branch is made up of two banks:
Branch 0 contains banks A and C
Branch 1 contains banks B and D
Online spare FBDIMM configuration requirements (in addition to general configuration requirements):
When only bank A is being used, it must be fully populated with dual-rank FBDIMMs.
If banks A and C are being used, they must be fully populated.
If installed, bank A and bank C must contain FBDIMMs with identical part numbers.
If installed, bank B and bank D must also contain FBDIMMs with identical part numbers.
In online spare mode, FBDIMMs must be populated as specified in the following table:
QuickSpecs
HP ProLiant DL380 Generation 5
Memory
DA - 12477 Worldwide QuickSpecs — Version 1 — 6/26/2006 Page 32