Dell PowerEdge M420 Dell PowerEdge M520 Systems Owner's Manual - Page 33

Memory Mirroring Memory Mirroring offers the strongest DIMM 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 DIMMs. In the event of an uncorrectable error, the system will switch over to the mirrored copy. This ensures SDDC and multi-bit protection. Memory installation guidelines: NOTE: The first memory channel for each processor (Channel 1) is disabled and not available for Memory Mirroring. • Memory channels 2 and 3 must be populated. • Memory modules must be identical in size, speed, and technology. • DIMMs installed in memory sockets with white release tabs must be identical and similar rule applies for sockets with black release tabs. For example, DIMMs installed in sockets A2 and A3 must be identical. Sample Memory Configurations The following tables show sample memory configurations that follow the appropriate memory guidelines stated in this section. NOTE: 16 GB quad-rank RDIMMs are not supported. NOTE: 1R and 2R in the following tables indicate single- and dual-rank DIMMs. Table 1. Memory Configurations - Single Processor System Capacity (in GB) 2 DIMM Size (in GB) 2 Number of DIMMs 1 4 2 2 10 2 5 12 4 3 20 4 5 24 8 3 32 8 4 48 16 3 96 16 6 Organization and Speed 1R x8, 1333 MT/s 1R x8, 1600 MT/s 1R x8, 1333 MT/s 1R x8, 1600 MT/s 1R x8, 1333 MT/s 1R x8, 1600 MT/s 1R x8, 1333 MT/s 1R x8, 1600 MT/s 1R x8, 1333 MT/s 1R x8, 1600 MT/s 2R x4, 1333 MT/s 2R x4, 1600 MT/s 2R x4, 1333 MT/s 2R x4, 1600 MT/s 2R x4, 1333 MT/s 2R x4, 1600 MT/s 2R x4, 1333 MT/s 2R x4, 1600 MT/s DIMM Slot Population A1 A1, A2 A1, A2, A3, A4, A5 A1, A2, A3 A1, A2, A3, A4, A5 A1, A2, A3 A1, A2, A3, A4 A1, A2, A3 A1, A2, A3, A4, A5, A6 33