Wear Levelling
Definition
A flash controller algorithm that distributes write operations across all blocks evenly to prevent any single block from wearing out prematurely. A side effect is that logically deleted data may be physically stored in a block the controller has not yet selected for erasure, making recovery possible longer than expected.
- Function
- Evenly distributes writes across flash memory blocks
- Purpose
- Prevents premature wear of any single block
- Forensic effect
- Deleted data can persist longer than expected in unerased blocks
- Relevant to
- Mobile device deleted-data recovery
Common questions
Why can deleted data survive longer on a flash device because of wear levelling?+
The controller schedules block erasure on its own timetable to spread wear evenly, so a logically deleted block may sit unerased for some time. Until the controller selects it for erasure, the original data remains physically present and potentially recoverable.
Does wear levelling guarantee that deleted data can always be recovered?+
No. Recovery is opportunistic and depends on how soon the controller erases the block, how much subsequent write activity has occurred, and whether the examiner has the chip-level or forensic-tool access needed to read unmapped pages.
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