Data Erasure: Clear, Purge, Destroy and How to Verify
Erasure is a claim that needs evidence. Clear, Purge and Destroy have different guarantees and different verification.
Classes
Clear overwrites with logical techniques; Purge uses stronger methods (crypto-erase, block erase) valid for media reuse; Destroy makes recovery physically impossible.
Verification
Verify by sampling with the same class of tool used to erase, keep logs and certificates, and for crypto-erase prove the key was destroyed. HDDs and SSDs need different verification.
FAQ
Is a single overwrite enough?
For most modern HDDs, yes; SSDs need crypto-erase or physical destruction.
Do I need a certificate?
For compliance and audit, yes — with method, scope and verification results.