Storage zeroing is the practice of overwriting reused disk, block, or memory-backed storage so previous contents cannot be recovered by the next user or tenant. In cloud systems, this usually means clearing freed blocks before they are reassigned to another workload, instead of simply marking them available for reuse.
It matters because deleted data can linger as residual bytes, also called data remanence. In multi-tenant environments, a missing zeroing step can let one customer read fragments of another customer’s files, metadata, or database pages from shared infrastructure. Defenders reduce this risk with zero-on-release controls, secure wipe routines, and tests that try to recover stale data after teardown. Attackers look for exactly these cleanup failures, because they can expose information even when runtime isolation is otherwise strong.