•
DIMMs installed in memory sockets with white release levers must be identical and the same rule applies for sockets with black release
levers. This ensures that identical DIMMs are installed in matched pair —for example, A1 with A2, A3 with A4, A5 with A6, and so on.
Memory optimized (independent channel) mode
This mode supports Single Device Data Correction (SDDC) only for memory modules that use x4 device width. It does not impose any
specific slot population requirements.
Memory sparing
NOTE:
To use memory sparing, this feature must be enabled in System Setup.
In this mode, one rank per channel is reserved as a spare. If persistent correctable errors are detected on a rank, the data from this rank is
copied to the spare rank, and the failed rank is disabled.
With memory sparing enabled, the system memory available to the operating system is reduced by one rank per channel. For example, in a
dual-processor configuration with sixteen 4 GB single-rank memory modules, the available system memory is: 3/4 (ranks/channel) × 16
(memory modules) × 4 GB = 48 GB, and not 16 (memory modules) × 4 GB = 64 GB.
NOTE:
Memory sparing does not offer protection against a multi-bit uncorrectable error.
NOTE:
Both Advanced ECC/Lockstep and Optimizer modes support memory sparing.
Memory mirroring
Memory mirroring offers the strongest memory module reliability mode compared to all other modes, providing improved uncorrectable
multi-bit failure protection. In a mirrored configuration, the total available system memory is one half of the total installed physical memory.
Half of the installed memory is used to mirror the active memory modules. In the event of an uncorrectable error, the appliance switches
over to the mirrored copy. This ensures SDDC and multi-bit protection.
The installation guidelines for memory modules are as follows:
•
Memory modules must be identical in size, speed, and technology.
•
Memory modules installed in memory module sockets with white release levers must be identical and the same rule applies for sockets
with black and green release tabs. This ensures that identical memory modules are installed in matched pairs—for example, A1 with A2,
A3 with A4, A5 with A6, and so on.
Table 26. Processor configuration
Processor
Configuration
Memory population rules
Memory population information
Single CPU
Memory population order
{1,2}, {3,4}
See Memory mirroring note
Sample memory configurations
The following tables show sample memory configurations for one and two processor configurations that follow the appropriate memory
guidelines.
NOTE:
1R, 2R, and 4R in the following tables indicate single, dual, and quad-rank DIMMs respectively.
60
Installing and removing components
