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Kubernetes Persistent Volume

Advanced Features on K8s with Cloud Volumes ONTAP: Scaling, Monitoring, and More

BlueXP Cloud Volumes ONTAP is a software-defined storage solution that provisions persistent storage for containerized workloads deployed on Kubernetes. As a comprehensive storage orchestration platform, Cloud Volumes ONTAP offers high performance, robust data protection, and non-disruptive operations for stateful workloads.

With Cloud Volumes ONTAP as the backend storage management system for your Kubernetes clusters, you can:

  • Easily deploy persistent storage for containerized workloads on any Kubernetes platform
  • Get all the features and benefits of the award-winning NetApp ONTAP software in a flexible, easy-to-deploy package
  • Benefit from the added efficiency of using containers with the robustness of enterprise-grade storage

You can also extend your on-premises data center to the cloud, consolidate multiple workloads in the cloud, build a new cloud-native application, and more.

In this article, we’ll discuss advanced Cloud Volumes ONTAP features for Kubernetes-based stateful applications and how they enable the effortless scaling and portability of Kubernetes persistent volumes.

Jump down to a topic in this post:

Streamline Existing Volumes

Cloud Volumes ONTAP provides a unified interface for hybrid cloud environments, managing both on-premises and cloud-based storage, making it easy to transition between the two. With it, organizations can quickly and easily create new storage volumes, add or remove capacity, create snapshots, and replicate data for backup or disaster recovery copies. In addition, Cloud Volumes ONTAP offers advanced storage efficiency features such as data compression and deduplication to help reduce storage costs.

Cloud Volumes ONTAP leverages Astra Trident, a CSI-compliant volume provisioning and management solution, to integrate with Kubernetes clusters for robust and flexible persistent storage. The platform provides a unified experience and control for Kubernetes persistent volumes across popular cloud platforms. Using NetApp SnapMirror®, Cloud Volumes ONTAP also simplifies data protection of Kubernetes workloads with automatic volume snapshots, backups, and disaster recovery.

Cloud Volumes ONTAP offers numerous options to streamline existing volumes for Kubernetes, such as:

Volume Import

Cloud Volumes ONTAP helps with the seamless migration of external volumes to a Kubernetes deployment by allowing you to move data to the cloud quickly and easily through a self-service interface. In a few simple steps, you can select the volumes to be moved, specify the destination account and region, and then Cloud Volumes ONTAP takes care of the rest. This includes transferring data to the cloud and creating necessary snapshots for rolling back changes if needed. You can also migrate data between distributed clusters and rebuild a compromised Kubernetes cluster by importing a volume from the backup site during disaster recovery.

Volume Resize

The integration of Cloud Volumes ONTAP with Kubernetes through Trident CSI allows for seamless volume expansion of both file and block storage by providing automatic provisioning and scaling features, without the need for manual intervention. In addition, Cloud Volumes ONTAP offers various non-disruptive volume resizing options to help you change volume sizes, deleted volume snapshots copies, and adjust reserve levels for snapshots.

Another approach is to leverage Cloud Volumes ONTAP data tiering. This feature automatically moves infrequently used data from block to low cost object storage and will move it back when needed. This feature will help save costs and also allows you to quickly free up block storage capacity without having to go through the provisioning and reconfiguring processes.

Control Storage Resources

Kubernetes allows cluster administrators to limit the consumption of storage resources by using resource quotas at the namespace or service level. With resource quotas, you can configure the allocation of storage volumes to avoid resource depletion and conflicts. A typical approach is to hard-limit aggregate storage consumption within a namespace by the disk type and total containerized workloads storage capacity.

Astra Trident Quotas

Cloud Volumes ONTAP supports both Kubernetes ResourceQuota and Trident Quotas to help enforce storage consumption limits within a Kubernetes cluster. By using both, you can granularly control storage usage, prevent over-consumption, and ensure workloads have the storage they need to function optimally.

Kubernetes uses the ResourceQuota object for limiting resource consumption by a given namespace. It can be used to limit the number of pods, services, or other objects in a namespace. Trident Quotas, on the other hand, are designed specifically for Cloud Volumes ONTAP and provide more fine-grained control over storage consumption by limiting the total size or number of volumes or snapshots for a specific Trident storage backend.

To offer granular control over managing volume capacity, Trident employs a number of configuration options to restrict resource usage limits and ensure volumes stay within their quotas.

  • limitVolumeSize - Restricts the provisioning of a volume if the volume claim is beyond the maximum allocated size. The limit is also enforced when a user requests a volume resize.
  • limitAggregateUsage - Restricts the provisioning of a volume if the volume claim exceeds the aggregate size beyond this limit. This limit is usually expressed as a percentage of the total aggregate physical storage capacity.
  • Using system-node-critical as a PriorityClass object - Identifies and optimizes storage volumes under resource strain while overriding other non-critical node behaviors.
  • qtreesPerFlexvol - Allows for more granular organization and management of data within the file storage system while providing additional flexibility by creating more PVCs within a single ONTAP volume in the backend.
  • lunsPerFlexvol - Enables specifying the maximum number of LUNs (logical unit numbers) that can be created within a single FlexVol volume for offering granular control on managing volume capacity and ensuring that volumes stay within their quotas.

Storage Monitoring with Prometheus

Prometheus is a time series database that enables highly scalable, out-of-the-box observability of distributed Kubernetes clusters. Integrating Cloud Volumes ONTAP with Prometheus allows you to collect and query metrics from your storage systems. This extends the power of Prometheus by adding support for NetApp's unique APIs and data structures, allowing you to get granular visibility into the performance and health of your Cloud Volumes storage systems.

With this add-on, you can query throughput, latency, IOPS, and other storage volume performance metrics. You can also use Grafana to create custom dashboards and alarms that notify you of potential capacity issues.

Monitoring Storage Metrics with Prometheus

Trident offers a number of Prometheus metric endpoints to enable the monitoring of a cluster’s storage performance. You can install Prometheus as an operator in the cluster and configure it to consume Trident metrics using a ServiceMonitor object that listens on the metrics port and watches the trident-csi service. With the metrics provided by the Trident Prometheus endpoint, administrators can:

  • Inspect if Trident has been configured correctly to communicate with the storage framework
  • Extract storage consumption details, such as the amount of space consumed and number of volumes provisioned in the Cloud Volumes ONTAP backend
  • Map the number of volumes provisioned on the available storage backends
  • Track performance by monitoring the time taken by Trident to communicate with storage backends

The benefits of using Prometheus to monitor Cloud Volumes ONTAP storage backend include:

  • Maintains a mapping of volumes provisioned by Cloud Volumes ONTAP through the Prometheus service monitor
  • Faster query speeds with PromQL
  • Helps with performance optimization and vulnerability mitigation through continuous monitoring

Supports Telemetry

Telemetry of Kubernetes storage is a centralized monitoring and logging process that helps keep track of events and performance data of the Kubernetes storage subsystem. The process is one of the key aspects that supports comprehensive observability of cluster health and identifies potential anomalies.

Support for Trident Telemetry with BlueXP Digital Advisor

NetApp’s BlueXP digital advisor helps simplify the proactive optimization and management of Cloud Volumes ONTAP storage backends in a number of ways. This includes collecting telemetry data from the Trident CSI, real-time monitoring of key performance indicators, alerting on potential problems, and providing AI-based recommendations for remediation. BlueXP digital advisor actively scans for issues such as volume misconfigurations, failing hardware, outdated firmware, and security vulnerabilities in the storage backend to ensure that cluster data is always available and robustly secure.

The benefits of leveraging BlueXP digital advisor for telemetry of Cloud Volumes ONTAP backend include:

  • Tracks storage usage, performance, and capacity in real time
  • Offers historical data of storage system performance
  • Uses advanced AI/ML models to perform proactive identification and mitigation of storage risks
  • Offers customizable dashboards and alerts

Performance and Capacity Scaling

Kubernetes ships with several features such as the volume expansion, which enables the dynamic resizing of volumes to match workload requirements. This operating construct relies on a flexible storage backend and offers the ability to scale storage capacity for cost and performance optimization. With Cloud Volume ONTAP, you can manage the persistent storage of hybrid cloud clusters more efficiently and scale your storage capacity as needed without having to provision new hardware.

Maintaining Optimal Performance

Leveraging low-latency connections with volume disks, Cloud Volumes ONTAP aggregates enable enhanced scalability of storage without interrupting workloads and cluster operations. Some features that enable optimal performance include:

  • On-demand provisioning allow dynamic and high-performant scale up and down of persistent volumes
  • Quality of service policies enforce consistent performance for critical applications and prevent Kubernetes workloads from impacting storage performance by continuous monitoring
  • Uses a scale-out cluster of multiple nodes; with each having its own flash storage for rapid read/write cache and high IOPS
  • Uses a combination of flash and hard disk storage modes to offer the optimum performance requirement of a workload
  • Efficient caching and compression capabilities that help improve storage performance and efficiency

Capacity Scaling

Cloud Volumes ONTAP utilizes license stacking and storage tiering for bypassing storage size limitations and achieve storage scaling into petabytes without incurring additional compute expenses. Features that support effective storage scaling include:

  • Automated storage tiering - Cloud Volumes ONTAP offers an automated storage tiering feature that can help you optimize your capacity utilization and costs. This feature automatically moves infrequently-used data from block to lower-cost object storage and back when needed. This will free up space for more active data and will save on storage costs while still ensuring that your data is available when you need it.
  • Automatic capacity management - BlueXP automatically provisions and configures capacity in response to changing workload demands, eliminating the need for manual capacity planning and management. This ensures that you always have the right amount of storage capacity available, without overprovisioning or underutilizing your resources.


As enterprises move more of their workloads to the cloud, they need to be able to rely on their cloud storage solutions to provide visibility and control over their data. BlueXP Cloud Volume ONTAP is a storage solution that helps customers do just that, by providing them with powerful yet easy-to-use tools for managing their data in the cloud.

With Cloud Volume ONTAP, enterprises can take advantage of all the benefits of the cloud – scalability, agility, and cost efficiency – while still maintaining the observability of their data. Additionally, Cloud Volume ONTAP provides built-in data protection and disaster recovery capabilities, so enterprises have peace of mind knowing that their data is safe and protected. Learn more in these Kubernetes Workloads with Cloud Volumes ONTAP Success Stories.

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Michael Shaul, Principal Technologist

Principal Technologist