DirectPV

DirectPV is a CSI driver for Direct Attached Storage. In a simpler sense, it is a distributed persistent volume manager, and not a storage system like SAN or NAS.

It is useful to discover, format, mount, schedule and monitor drives across servers. Since Kubernetes hostPath and local PVs are statically provisioned and limited in functionality, DirectPV was created to address this limitation.

Distributed data stores such as object storage, databases and message queues are designed for direct attached storage, and they handle high availability and data durability by themselves. Running them on traditional SAN or NAS based CSI drivers (Network PV) adds yet another layer of replication/erasure coding and extra network hops in the data path. This additional layer of disaggregation results in increased-complexity and poor performance.

Direct Persistent Volume vs Network Persistent Volume

Architecture

DirectPV is designed to be lightweight and scalable to tens of thousands of drives. It is made up of three components - Controller, Node Driver, UI.

Architecture
Controller

Controller

When a volume claim is made, the controller provisions volumes uniformly from a pool free drives. DirectPV is aware of pod's affinity constraints, and allocates volumes from drives local to pods. Note that only one active instance of controller runs per cluster.

Node Driver

Node Driver

Node Driver implements the volume management functions such as discovery, format, mount, and monitoring of drives on the nodes. One instance of node driver runs on each of the storage servers.

UI

UI

Storage Administrators can use the kubectl CLI plugin to select, manage and monitor drives. Web based UI is currently under development.

Installation

Install the kubectl DirectPV plugin.

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kubectl krew install directpv

Use the plugin to install DirectPV in your Kubernetes cluster.

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kubectl directpv install

Ensure that DirectPV has successfully started.

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kubectl directpv info

List the available drives in your cluster.

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kubectl directpv drives ls

Select the drives that DirectPV should manage and format.

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kubectl directpv drives format —drives /dev/sd{a…f} —nodes directpv-{1…4}

directpv can now be specified as the storageclass in PodSpec.VolumeClaimTemplates.

For air-gapped setups and advanced installations, please refer to the Installation Guide.

Upgrade

DirectPV version upgrades are seamless and transparent. Simply uninstall an existing version of directpv and install with a newer version to upgrade.

Uninstall DirectPV from your Kubernetes setup.

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kubectl directpv uninstall

Download the latest krew plugin.

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kubectl krew upgrade directpv

Install DirectPV using the new plugin.

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kubectl directpv install

Security

Please review the security checklist before deploying to production.

Important: Report security issues to security@min.io. Please do not report security issues here.

Additional Resources

Join the Community

DirectPV is a MinIO project. You can contact the authors over the Slack channel:

Join the Community MinIO Slack

License

DirectPV is released under GNU AGPLv3 license. Please refer to the LICENSE document for a complete copy of the license.

License