Volume Encryption (VE) is a software-based technology for encrypting data at rest one volume at a time. An encryption key accessible only to the storage system ensures that volume data cannot be read if the underlying device is repurposed, returned, misplaced, or stolen.

Understanding VE

With VE, both metadata and data (including Snapshot copies) are encrypted. Access to the data is given by a unique XTS-AES-256 key, one per volume. An external key management server or Onboard Key Manager (OKM) serves keys to nodes:

The external key management server is a third-party system in your storage environment that serves keys to nodes using the Key Management Interoperability Protocol (KMIP). It is a best practice to configure external key management servers on a different storage system from your data.
The Onboard Key Manager is a built-in tool that serves keys to nodes from the same storage system as your data.

Aggregate and volume encryption is enabled by default if you have a volume encryption (VE) license and use an onboard or external key manager. The VE license is included with ONTAP One. Whenever an external or onboard key manager is configured there is a change in how the encryption of data at rest is configured for brand new aggregates and brand new volumes. Brand new aggregates will have Aggregate Encryption (AE) enabled by default. Brand new volumes that are not part of an AE aggregate will have Volume Encryption (VE) enabled by default. If a data storage virtual machine (SVM) is configured with its own key-manager using multi-tenant key management, then the volume created for that SVM is automatically configured with VE.

You can enable encryption on a new or existing volume. VE supports the full range of storage efficiency features, including deduplication and compression. Beginning with ONTAP 9.14.1, you can enable VE on existing SVM root volumes.

If you are using SnapLock, you can enable encryption only on new, empty SnapLock volumes. You cannot enable encryption on an existing SnapLock volume.

You can use VE on any type of aggregate (HDD, SSD, hybrid, array LUN), with any RAID type, and in any supported ONTAP implementation. You can also use VE with hardware-based encryption to “double encrypt” data on self-encrypting drives.

When VE is enabled, the core dump is also encrypted.

Aggregate-level encryption

Ordinarily, every encrypted volume is assigned a unique key. When the volume is deleted, the key is deleted with it.

You can use Aggregate Encryption (AE) to assign keys to the containing aggregate for the volumes to be encrypted. When an encrypted volume is deleted, the keys for the aggregate are preserved. The keys are deleted if the entire aggregate is deleted.

You must use aggregate-level encryption if you plan to perform inline or background aggregate-level deduplication. Aggregate-level deduplication is otherwise not supported by VE.

Aggregate and volume encryption is enabled by default if you have a volume encryption (VE) license and use an onboard or external key manager.

VE and AE volumes can coexist on the same aggregate. Volumes encrypted under aggregate-level encryption are AE volumes by default. You can override the default when you encrypt the volume.

You can use the volume move command to convert an VE volume to an AE volume, and vice versa. You can replicate an AE volume to an VE volume.

You cannot use secure purge commands on an AE volume.

When to use external key management servers

Although it is less expensive and typically more convenient to use the onboard key manager, you should set up KMIP servers if any of the following are true:

Your encryption key management solution must comply with Federal Information Processing Standards (FIPS) 140-2 or the OASIS KMIP standard.
You need a multi-cluster solution, with centralized management of encryption keys.
Your business requires the added security of storing authentication keys on a system or in a location different from the data.

Scope of external key management

The scope of external key management determines whether key management servers secure all the SVMs in the cluster or selected SVMs only:

You can use a cluster scope to configure external key management for all the SVMs in the cluster. The cluster administrator has access to every key stored on the servers.
You can use an SVM scope to configure external key management for a named SVM in the cluster. That’s best for multitenant environments in which each tenant uses a different SVM (or set of SVMs) to serve data. Only the SVM administrator for a given tenant has access to the keys for that tenant.

You can use both scopes in the same cluster. If key management servers have been configured for an SVM, ONTAP uses only those servers to secure keys. Otherwise, ONTAP secures keys with the key management servers configured for the cluster.

Support details

The following table shows VE support details:

Resource or feature	Support details
Platforms	AES-NI offload capability required.
Encryption	Newly created aggregates and volumes are encrypted by default when you add a volume encryption (VE) license and have an onboard or external key manager configured. If you need to create an unencrypted aggregate, use the following command: `storage aggregate create -encrypt-with-aggr-key false` If you need to create a plain text volume, use the following command: `volume create -encrypt false` Encryption is not enabled by default when: VE license is not installed. Key manager is not configured. Platform or software does not support encryption. Hardware encryption is enabled.
ONTAP	All ONTAP implementations. Support for ONTAP Cloud is available in ONTAP 9.7 and later.
Devices	HDD, SSD, hybrid, array LUN.
RAID	RAID0, RAID4, RAID-DP, RAID-TEC.
Volumes	Data volumes and existing SVM root volumes. You cannot encrypt data on MetroCluster metadata volumes. In versions of ONTAP earlier than 9.14.1, you cannot encrypt data on the SVM root volume with VE. Beginning with ONTAP 9.14.1, ONTAP supports VE on SVM root volumes.
Aggregate-level encryption	VE supports aggregate-level encryption (AE): You must use aggregate-level encryption if you plan to perform inline or background aggregate-level deduplication. You cannot rekey an aggregate-level encryption volume. Secure-purge is not supported on aggregate-level encryption volumes. In addition to data volumes, AE supports encryption of SVM root volumes and the MetroCluster metadata volume. AE does not support encryption of the root volume.
SVM scope	VE supports SVM scope for external key management only, not for Onboard Key Manager. MetroCluster is supported beginning with ONTAP 9.8.
Storage efficiency	Deduplication, compression, compaction, FlexClone. Clones use the same key as the parent, even after splitting the clone from the parent. You should perform a `volume move` on a split clone, after which the split clone will have a different key.
Replication	For volume replication, the source and destination volumes can have different encryption settings. Encryption can be configured for the source and unconfigured for the destination, and vice versa. For SVM replication, the destination volume is automatically encrypted, unless the destination does not contain a node that supports volume encryption, in which case replication succeeds, but the destination volume is not encrypted. For MetroCluster configurations, each cluster pulls external key management keys from its configured key servers. OKM keys are replicated to the partner site by the configuration replication service.
Compliance	SnapLock is supported in both Compliance and Enterprise modes, for new volumes only. You cannot enable encryption on an existing SnapLock volume.
FlexGroups	FlexGroups are supported. Destination aggregates must be of the same type as source aggregates, either volume-level or aggregate-level. In-place rekey of FlexGroup volumes is supported.

Resource or feature

Support details

Platforms

AES-NI offload capability required.

Encryption

Newly created aggregates and volumes are encrypted by default when you add a volume encryption (VE) license and have an onboard or external key manager configured. If you need to create an unencrypted aggregate, use the following command:

storage aggregate create -encrypt-with-aggr-key false

If you need to create a plain text volume, use the following command:

volume create -encrypt false

Encryption is not enabled by default when:

VE license is not installed.
Key manager is not configured.
Platform or software does not support encryption.
Hardware encryption is enabled.

ONTAP

All ONTAP implementations. Support for ONTAP Cloud is available in ONTAP 9.7 and later.

Devices

HDD, SSD, hybrid, array LUN.

RAID

RAID0, RAID4, RAID-DP, RAID-TEC.

Volumes

Data volumes and existing SVM root volumes. You cannot encrypt data on MetroCluster metadata volumes. In versions of ONTAP earlier than 9.14.1, you cannot encrypt data on the SVM root volume with VE. Beginning with ONTAP 9.14.1, ONTAP supports VE on SVM root volumes.

Aggregate-level encryption

VE supports aggregate-level encryption (AE):

You must use aggregate-level encryption if you plan to perform inline or background aggregate-level deduplication.
You cannot rekey an aggregate-level encryption volume.
Secure-purge is not supported on aggregate-level encryption volumes.
In addition to data volumes, AE supports encryption of SVM root volumes and the MetroCluster metadata volume. AE does not support encryption of the root volume.

SVM scope

VE supports SVM scope for external key management only, not for Onboard Key Manager. MetroCluster is supported beginning with ONTAP 9.8.

Storage efficiency

Deduplication, compression, compaction, FlexClone.

Clones use the same key as the parent, even after splitting the clone from the parent. You should perform a volume move on a split clone, after which the split clone will have a different key.

Replication

For volume replication, the source and destination volumes can have different encryption settings. Encryption can be configured for the source and unconfigured for the destination, and vice versa.
For SVM replication, the destination volume is automatically encrypted, unless the destination does not contain a node that supports volume encryption, in which case replication succeeds, but the destination volume is not encrypted.
For MetroCluster configurations, each cluster pulls external key management keys from its configured key servers. OKM keys are replicated to the partner site by the configuration replication service.

Compliance

SnapLock is supported in both Compliance and Enterprise modes, for new volumes only. You cannot enable encryption on an existing SnapLock volume.

FlexGroups

FlexGroups are supported. Destination aggregates must be of the same type as source aggregates, either volume-level or aggregate-level. In-place rekey of FlexGroup volumes is supported.