HP ProLiant DL380 G5 - Page 22

Mirrored memory configuration
Mirrored memory configurationMirrored memory configuration
Mirrored memory configuration
Mirroring provides protection against uncorrectable memory errors that would otherwise result in server downtime.
Mirroring is performed on the branch level. Branch 0 and branch 1 mirror each other.
Each branch maintains a copy of all memory contents. Memory writes go to both branches. Memory reads come from only one of
the two branches (unless an uncorrectable error occurs). If a memory read on one branch returns incorrect data due to an
uncorrectable memory error, the system automatically retrieves the proper data from the other branch. A branch is not necessarily
disabled (thus losing mirroring protection) because of a single uncorrectable error. Mirroring protection is not lost due to transient
and soft uncorrectable errors, resulting in systems that maintain mirroring protection (and thus improved uptime) unless there is a
true FBDIMM failure.
Because both branches are active, concurrent reads from both branches at the same time are possible. Therefore, mirroring provides
superior read performance compared to all other Advanced Memory Protection modes.
Mirrored memory FBDIMM configuration requirements (in addition to general configuration requirements):
Banks A and B must be fully populated.
Bank A and bank B must contain FBDIMMs with identical part numbers. If installed, bank C and bank D must also contain
FBDIMMs with identical part numbers.
When using mirrored memory mode, FBDIMMs must be populated as specified in the following table:
Configuration
ConfigurationConfiguration
Configuration
Bank A
Bank ABank A
Bank A
1A and 3A
1A and 3A1A and 3A
1A and 3A
Bank B
Bank BBank B
Bank B
5B and 7B
5B and 7B5B and 7B
5B and 7B
Bank C
Bank CBank C
Bank C
2C and 4C
2C and 4C2C and 4C
2C and 4C
Bank D
Bank DBank D
Bank D
6D and 8D
6D and 8D6D and 8D
6D and 8D
1 X X - -
2 X X X X
NOTE:
NOTE:NOTE:
NOTE: After installing FBDIMMs, use RBSU to configure the system for mirrored memory support ("Configuring mirrored memory" on
page 57).
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DA - 12559 North America — Version 1 — September 12, 2006 Page 22