HP ProLiant BL620c G7 Server-Blade - Manual (Page 46)

Hardware options installation 46
Mirrored Memory population guidelines
Errors that are not corrected by ECC, SDDC, or DDDC cannot be corrected by Online Spare memory. By
providing added redundancy in the memory sub-system, Mirrored Memory provides the greatest protection
against memory failure beyond ECC, SDDC, DDDC, and Online Spare memory.
In Mirrored Memory mode, each Lockstep DIMM pair of a memory controller has a mirrored DIMM pair on
the other memory controller of the same processor.
Upon detecting an uncorrectable memory error from a DIMM pair of a memory controller, the processor
avoids a system crash by reading the mirrored DIMM pairs from the other memory controller. In this case, the
system management routine disables the failed DIMM. Further memory reads and writes occur only on the
mirrored DIMM pairs.
The exceptions to Mirrored Memory mode are the following:
• In Mirrored Memory mode, half of the memory is allocated to memory protection.
• The available memory bandwidth is reduced by up to 50% in this mode.
• Mirrored Memory mode, Online Spare mode, Hemisphere mode, and interleaving cannot be enabled
simultaneously.
To configure memory for Mirrored Memory mode, observe these additional constraints:
• For the server to support Mirrored Memory, all processors must have a valid mirroring configuration.
• The minimum allowable configuration is four DIMMs per processor.
• Both memory controllers for each processor must be populated with the same DIMM configurations.
• Although this configuration requirement is the same for Hemisphere mode and Mirrored Memory mode,
only one of the two modes can be enabled at a given time.
Installing DIMMs
To install the component:
1. Power down the server blade (on page 14 ).
2. Remove the server blade (on page 15 ).
3. Remove the access panel (on page 16 ).
4. Do one of the following:
o If installing processor 1 DIMMs, remove the right DIMM baffle (on page 18 ).
o If installing processor 2 DIMMs, remove the left DIMM baffle (on page 17 ).
5. Open the DIMM slot latches.