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Memory mirroring uses mirrored banks (on a single memory
board) to provide a high level of memory redundancy. This
feature provides protection against multi-bit error without
degrading the performance of the memory system.
DIMM Capacity and Configuration Requirements
- Memory is 4-way interleaved and as a result the DIMMs
must be installed in banks consisting of 4 DIMMs per bank.
- The DIMMs in a bank must be of the same capacity, manufacturer
and have the same SPD characteristics. No mixing of memory
DIMMs is allowed.
- DIMM must install Bank #1 and Bank #3. Bank #2 must not
install any DIMMs, because Bank #2 does not have mirror
bank.
Below table list the install bank of memory mirroring.
| |
Bank #1(Active Bank) |
Bank #2 |
Bank #3(Mirror Bank) |
|
4 DIMM configuration
|
Install |
Not Install |
Not Install |
Not Available |
8 DIMM configuration
|
Install |
Not Install |
Install |
Available |
| 12 DIMM configuration |
Install |
Install |
Install |
Not Available |
NOTE. Only one of the banks will be read (Bank #1, by default),
for instance, if 8 x 1 GB DIMMs are installed, only 4 Gigabytes
of that 8 Gigabytes is available for use by the operating
system.
How Memory Mirroring FunctionsIn
normal operation mode, System writes memory data to Bank
#1 and Bank #3. And, reads memory data from Bank #1. If system
detected uncorrectable error at Bank #1, system re-read memory
data from Bank #3. If system detected uncorrectable error,
system degenerates error bank and records the error logs,
and blink system's status LED.
If system detected uncorrectable error both bank (Bank #1
and Bank #3), System could not recover the error. Therefore,
if system detected uncorrectable error both bank, system will
assert fatal error.
If system detect correctable error at mirror mode, system
degenerate error bank. System only record correctable error
logs.
If system sets memory mirroring function, system could not
use memory sparing function at a same time.
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