You need to configure data-at-rest encryption for your NetApp ONTAP 9.

 To configure data-at-rest encryption for your NetApp ONTAP 9.8 cluster without KMIP services, you need to enable onboard key management and cluster-wide FIPS-compliant mode. Onboard key management allows you to use a passphrase to generate and protect the cluster-wide encryption key, which is used to encrypt the disk encryption keys. Cluster-wide FIPS-compliant mode ensures that the encryption algorithms and modules used by ONTAP are compliant with the Federal Information Processing Standard (FIPS) 140-2. These two actions will satisfy the requirements of data security and passphrase protection for your cluster. References :- NetApp Encryption overview, Configure onboard key management, Enable cluster-wide FIPS-compliant mode