Dell 1955 owner manual Memory Mirroring

Table 3-1. Memory Sparing Configurations

Memory Module Size/Type	Total Memory	Available Memory	Spare Memory
Eight 256-MB single-rank modules	2 GB	1 GB	1 GB
Eight 512-MB single-rank modules	4 GB	2 GB	2 GB
Eight 1-GB single-rank modules	8 GB	4 GB	4 GB
Eight 2-GB single-rank modules	16 GB	8 GB	8 GB
Eight 2-GB dual-rank modules	16 GB	12 GB	4 GB
Eight 4-GB dual-rank modules	32 GB	24 GB	8 GB

The following guidelines apply to memory sparing:

•The system only supports memory sparing if eight identical memory modules are installed (same size, speed, technology, and vendor).

•Sparing is not supported if mirroring is enabled.

You can enable memory sparing through the System Setup program. See "Using the System Setup Program" on page 43.

Memory Mirroring

Memory mirroring provides additional data redundancy and system availability. The system divides the total memory in half and copies identical sets of data to each half. Consequently, the amount of available memory is half the amount of physical memory. If a memory module fails, the data in the mirrored data set is still available, and the system can operate normally until the memory module is replaced.

The following guidelines apply to memory mirroring:

•The system only supports memory mirroring if eight identical memory modules are installed.

•Mirroring is not supported if sparing is enabled.

You can enable memory mirroring through the System Setup program. See "Using the System Setup Program" on page 43.

Installing System Options

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