hesela.devReverse mapping (FTL)
An FTL reverse mapping associates a physical flash location with logical addresses that refer to its contents.
Historical page metadata need not describe every current reference after address sharing. Collection and recovery must reconcile the changed associations, rather than trust an obsolete address stored with the page. [1]
The logical-to-physical map serves host lookups; the reverse direction supports relocation and reconstruction. Neither mapping direction alone defines a flush or transaction guarantee. [1] [2]
In SCFTL, a stored physical-to-logical pair p to l is invalid if the current logical-to-physical map no longer sends l to p. The reverse entry can remain as history without making p live. [2]
Relations
- related
- Flash translation layer (FTL), Page-level mapping (FTL), Garbage collection (flash), Snapshot-consistent flash translation layer
Citations
- Zhou et al. Remap-SSD. FAST 2021, pp. 187-202, sections 2-4: reverse mappings and remapping consistency.
- Chang et al. Determinizing Crash Behavior with a Verified Snapshot-Consistent Flash Translation Layer. OSDI 2020, sections 3.2-3.4.