Flash memory controller: Difference between revisions

Revision as of 17:36, 3 February 2025

Revision as of 17:37, 3 February 2025

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As the FTL metadata takes up its own flash space, it needs protection in case of power loss. In addition, it is possible for the mapping table to wear out before other parts of the flash memory has, prematurely ending the life of a storage device. This is usually avoided in enterprise devices by allocating an oversized space for spares, although more durable forms of storage like [[Magnetoresistive RAM|MRAM]] has been proposed for FTL too.{{Citation needed|date=May 2023}}

The FTL may has three types: page mapping, block mapping and hybrid mapping. Page mapping can have higher performance, but it has bigger FTL metadata size and higher cost, and its usually used on [[solid state drive]]s. Block mapping can hashave smaller metadata size and lower cost, but it has lower performance, and its usually used on [[USB flash drive]]s. On page mapping FTL implementations, the ratio of FTL metadata size and storage capacity is usually 1:1000, for example, a 1TB flash storage device may has 1GB of FTL metadata.

==Garbage collection==