hesela.devBlock invalidation time
Block invalidation time is the point at which a stored block version becomes obsolete, rather than the duration for which it remained valid.
Equal lifetimes do not imply equal invalidation endpoints when versions were written at different times. [1]
SepBIT infers placement from user-write history and surviving GC-rewritten blocks, rather than assuming perfect knowledge of future invalidations. Its logical clock advances on user writes, not GC rewrites. [2]
Keep the observation unit explicit: elapsed seconds, intervening workload writes and physical erase cycles are different quantities.
Relations
- related
- Hot/cold data separation, Garbage collection (flash), Greedy garbage collection, Write amplification
Limitations
- An estimated invalidation time is not a guaranteed overwrite deadline, and a placement heuristic does not establish device-level write amplification. [2]
Citations
- He et al. The Unwritten Contract of Solid State Drives. EuroSys 2017, section 3.4. DOI: 10.1145/3064176.3064187.
- Wang et al. Separating Data via Block Invalidation Time Inference for Write Amplification Reduction in Log-Structured Storage. FAST 2022.
Further reading
Sources & caveats
- Primary-source synthesis; related age-conditioning arithmetic is explicitly hypothetical, not a hardware experiment or reproduction of the SepBIT prototype.