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Use balanced placement with ONTAP backends

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You can enable ONTAP balanced placement on ONTAP backends. With balanced placement, ONTAP selects the optimal aggregate for each new volume, so you do not need to manage aggregate assignment in Trident.

How balanced placement works

By default, Trident discovers the aggregates assigned to an SVM, treats each aggregate as a storage pool, and selects an aggregate when it provisions a volume.

When you enable balanced placement:

  • Trident reports the entire SVM as a single storage pool instead of reporting individual aggregates.

  • ONTAP selects the aggregate for each new volume and balances volumes across the available aggregates.

  • Trident creates volumes using the ONTAP /application/containers REST API.

Balanced placement is available for unified ONTAP systems (AFF, FAS, and ASA) and NetApp AFX storage systems.

Requirements

  • The backend must use ONTAP 9.19.1 or later.

  • Trident must communicate with ONTAP using REST. Balanced placement is not available with ZAPI.

  • The backend configuration must not specify aggregates. You cannot combine balanced placement with explicit aggregate selection.

Default values

The default value of useBalancedPlacement depends on the storage system:

Storage system Default Notes

Unified ONTAP (AFF, FAS, ASA)

false

Trident selects aggregates unless you enable balanced placement.

NetApp AFX (ONTAP 9.19.1 or later)

true

Balanced placement is required. Setting useBalancedPlacement to false causes backend validation to fail.

NetApp AFX (earlier than ONTAP 9.19.1)

false

Balanced placement is not available.

Configuration option

Parameter Description Default

useBalancedPlacement

Delegates aggregate selection for new volumes to ONTAP. Set this option at the root of the backend configuration or on individual virtual pools.

false; true for AFX on ONTAP 9.19.1 or later

Balanced placement with virtual pools

Balanced placement works with or without virtual pools:

  • Without virtual pools, Trident reports the SVM as a single storage pool and creates all new volumes using balanced placement.

  • With virtual pools, Trident reports the virtual pools and matches volumes to them as usual. If the matching virtual pool has balanced placement enabled, ONTAP selects the aggregate for the volume.

Set useBalancedPlacement at the root of the backend configuration to apply it to all virtual pools, or set it on individual virtual pools to enable it selectively.

Examples

The following example enables balanced placement on a unified ONTAP backend:

---
version: 1
storageDriverName: ontap-nas
backendName: nas-balanced-placement
managementLIF: 10.0.0.1
dataLIF: 10.0.0.2
svm: trident_svm
username: cluster-admin
password: <password>
useBalancedPlacement: true

The following example enables balanced placement using TridentBackendConfig:

apiVersion: trident.netapp.io/v1
kind: TridentBackendConfig
metadata:
  name: backend-tbc-ontap-nas
spec:
  version: 1
  storageDriverName: ontap-nas
  backendName: nas-balanced-placement
  managementLIF: 10.0.0.1
  svm: trident_svm
  useBalancedPlacement: true
  credentials:
    name: backend-tbc-ontap-nas-secret

The following example enables balanced placement on the gold virtual pool only. Trident continues to select aggregates for volumes that match the bronze virtual pool:

---
version: 1
storageDriverName: ontap-nas
backendName: nas-virtual-pools
managementLIF: 10.0.0.1
svm: trident_svm
username: cluster-admin
password: <password>
storage:
- labels:
    performance: gold
  useBalancedPlacement: true
- labels:
    performance: bronze

Backend validation errors

Backend creation or update fails in the following cases:

Configuration Result

useBalancedPlacement: true on ONTAP earlier than 9.19.1

Validation fails. Upgrade to ONTAP 9.19.1 or later.

useBalancedPlacement: true on a backend using ZAPI

Validation fails. Configure the backend to use REST.

useBalancedPlacement: true combined with specific aggregates

Validation fails. Remove the aggregate configuration or disable balanced placement.

useBalancedPlacement: false on AFX with ONTAP 9.19.1 or later

Validation fails. Balanced placement is required for AFX on ONTAP 9.19.1 or later.