Choosing a driver

To create and use an ONTAP backend, you will need:

Trident provides 5 unique storage drivers for communicating with ONTAP clusters. Each driver handles the creation of volumes and access control differently and their capabilities are detailed in this section.

Driver Protocol VolumeMode Access Modes Supported File Systems Supported
ontap-nas NFS Filesystem RWO,RWX,ROX "", nfs
ontap-nas-economy NFS Filesystem RWO,RWX,ROX "", nfs
ontap-nas-flexgroup NFS Filesystem RWO,RWX,ROX "", nfs
ontap-san iSCSI Block RWO,ROX,RWX No Filesystem. Raw block device
ontap-san-economy iSCSI Block RWO,ROX,RWX No Filesystem. Raw block device
ontap-san iSCSI Filesystem RWO,ROX xfs, ext3, ext4
ontap-san-economy iSCSI Filesystem RWO,ROX xfs, ext3, ext4


ONTAP backends can be authenticated by one of two means:
  • Login credentials for a security role [username/password] OR
  • Certificated-based, using the private key and the certificate that is installed on the ONTAP cluster.

Users can update existing backends to move from one authentication mode to the other with tridentctl update backend.

The ontap-san and ontap-san-economy drivers support the Filesystem and Block volumeModes. Users can choose to create a raw block volume with no file system (or) have Trident create a volume with a file system. For the latter, the fsType is specified through the Storage Class.

For example:

kind: StorageClass
name: netapp-san-economy
backendType: "ontap-san-economy"
fsType: "ext4"


Please refer to the NetApp Hardware Universe for up-to-date information on volume limits for your storage cluster. Based on the number of nodes, the platform and the version of ONTAP being used, these limits will vary.

The ontap-nas and ontap-san drivers create an ONTAP FlexVol for each PV. If your persistent volume requirements fit within that limitation, those drivers are the preferred solution due to the granular data management capabilities they afford.

If you need more persistent volumes than may be accommodated by the FlexVol limits, choose the ontap-nas-economy or the ontap-san-economy driver.

The ontap-nas-economy driver creates PVs as ONTAP Qtrees within a pool of automatically managed FlexVols. Qtrees offer far greater scaling at the expense of granular data management features. Users can configure the number of Qtrees created per FlexVol (between 50 and 300) for a backend. By default, a FlexVol created by Trident can contain 200 Qtrees.

The ontap-san-economy driver creates PVs as ONTAP LUNs within a pool of automatically managed FlexVols. Each PV maps to an ONTAP LUN and this driver offers higher scalability for SAN workloads. Since PVs map to LUNs within shared FlexVols, Kubernetes VolumeSnapshots are created using ONTAP’s FlexClone technology. FlexClone LUNs and their parent LUNs share blocks, minimizing disk usage.

Choose the ontap-nas-flexgroup driver to increase parallelism to a single volume that can grow into the petabyte range with billions of files. Some ideal use cases for FlexGroups include AI/ML/DL, big data and analytics, software builds, streaming, file repositories, etc. Trident uses all aggregates assigned to an SVM when provisioning a FlexGroup Volume. FlexGroup support in Trident also has the following considerations:

  • Requires ONTAP version 9.2 or greater.
  • With ONTAP 9.7, FlexGroups work with NFSv4. For ONTAP clusters that are running 9.6 and below, NFSv3 must be used (required to set mountOptions: ["nfsvers=3"] in the Kubernetes storage class).
  • When using NFSv3, it is recommended to enable the 64-bit NFSv3 identifiers for the SVM.
  • The minimum recommended FlexGroup size is 100GB.
  • Cloning FlexGroup volumes is supported with ONTAP 9.7 and above.

For information regarding FlexGroups and workloads that are appropriate for FlexGroups see the NetApp FlexGroup Volume - Best Practices and Implementation Guide.