A shallow rekey operation rotates only the Key Encryption Key (KEK). In vSAN Data-at-Rest Encryption, vCenter obtains or generates the KEK through the configured key provider, while ESX hosts use Data Encryption Keys (DEKs) to encrypt the actual disk or object data. The KEK is used to protect, or wrap, those DEKs. When a shallow rekey is performed, the underlying encrypted data does not need to be rewritten because the DEKs remain the same; only the KEK changes, and the existing DEKs are re-encrypted with the new KEK. This is why shallow rekey is faster and less disruptive than a deep rekey. A deep rekey generates both a new KEK and new DEKs, requiring re-encryption of data. The Host Key is used for encrypted core dumps, not datastore data encryption. Key Derivation Key is not the key rotated in this vSAN shallow rekey workflow. Reference topics: vSAN Data-at-Rest Encryption, Generate New Encryption Keys, Shallow Rekey, Deep Rekey, KEK and DEK lifecycle.