Memóriamirroringet

Memóriamirroringet, or memory mirroring, is a fault-tolerance technique used in computer systems to improve the reliability of volatile memory. In this approach, writes are duplicated across two or more memory modules or channels, and reads can be served from any mirror. The goal is to allow the system to continue operating even if one memory module fails or develops an uncorrectable error.

The basic mechanism relies on keeping mirror copies synchronized so that every write is applied to all copies. A memory controller or interconnect coordinates the duplication and ensures consistency, sometimes using lockstep or mirrored channels. Two common configurations are two-way mirroring, which uses two copies, and multi-way mirroring, which adds additional copies but increases hardware and power costs. Because data is stored in multiple places, the total usable memory capacity is reduced by the number of mirrors; for example, two-way mirroring provides the effective capacity of a single module.

Benefits and limitations accompany the design. Memory mirroring increases resilience against module failure and certain memory errors, reducing the chance of downtime due to RAM faults. However, it introduces write overhead, potential latency increases, and significant capacity overhead. It is not a substitute for backups or disaster recovery, since it protects memory reliability rather than protecting data against corruption, deletion, or loss in storage systems.

Typical use cases include mission-critical servers, financial systems, aerospace or industrial control systems, and other environments where continuous operation is prioritized. In practice, mirroring is chosen when high availability justifies the additional cost and reduced usable capacity.