Introduction

A Container Storage Interface (CSI) Driver for Kubernetes. The HPE CSI Driver for Kubernetes allows you to use a Container Storage Provider (CSP) to perform data management operations on storage resources. The architecture of the CSI driver allows block storage vendors to implement a CSP that follows the specification (a browser friendly version).

The CSI driver architecture allows a complete separation of concerns between upstream Kubernetes core, SIG Storage (CSI owners), CSI driver author (HPE) and the backend CSP developer.

HPE CSI Driver Architecture

Tip

The HPE CSI Driver for Kubernetes is vendor agnostic. Any entity may leverage the driver and provide their own Container Storage Provider.

Table of Contents

Features and Capabilities

CSI gradually mature features and capabilities in the specification at the pace of the community. HPE keep a close watch on differentiating features the primary storage family of products may be suitable for implementing in CSI and Kubernetes. HPE experiment early and often. That's why it's sometimes possible to observe a certain feature being available in the CSI driver although it hasn't been announced or isn't documented.

Below is the official table for CSI features we track and deem readily available for use after we've officially tested and validated it in the platform matrix.

Feature K8s maturity Since K8s version HPE CSI Driver
Dynamic Provisioning Stable 1.13 1.0.0
Volume Expansion Stable 1.24 1.1.0
Volume Snapshots Stable 1.20 1.1.0
PVC Data Source Stable 1.18 1.1.0
Raw Block Volume Stable 1.18 1.2.0
Inline Ephemeral Volumes Beta 1.16 1.2.0
Volume Limits Stable 1.17 1.2.0
Volume Mutator1 N/A 1.15 1.3.0
Generic Ephemeral Volumes GA 1.23 1.3.0
Volume Groups1 N/A 1.17 1.4.0
Snapshot Groups1 N/A 1.17 1.4.0
NFS Server Provisioner1 N/A 1.17 1.4.0
Volume Encryption1 N/A 1.18 2.0.0
Topology Stable 1.17 Future
Storage Capacity Tracking Stable 1.24 Future
Volume Expansion From Source Stable 1.27 Future
ReadWriteOncePod Stable 1.29 Future
Volume Populator Beta 1.24 Future
Volume Health Alpha 1.21 Future
Cross Namespace Snapshots Alpha 1.26 Future
Upstream Volume Group Snapshot Alpha 1.27 Future
Volume Attribute Classes Alpha 1.29 Future

1 = HPE CSI Driver for Kubernetes specific CSI sidecar. CSP support may vary.
2 = Alpha features are enabled by Kubernetes feature gates and are not formally supported by HPE.

Depending on the CSP, it may support a number of different snapshotting, cloning and restoring operations by taking advantage of StorageClass parameter overloading. Please see the respective CSP for additional functionality.

Refer to the official table of feature gates in the Kubernetes docs to find availability of beta and alpha features. HPE provide limited support on non-GA CSI features. Please file any issues, questions or feature requests here. You may also join our Slack community to chat with HPE folks close to this project. We hang out in #Alletra, #NimbleStorage, #3par-primera and #Kubernetes, sign up at slack.hpedev.io and login at hpedev.slack.com.

Tip

Familiarize yourself with the basic requirements below for running the CSI driver on your Kubernetes cluster. It's then highly recommended to continue installing the CSI driver with either a Helm chart or an Operator.

Compatibility and Support

These are the combinations HPE has tested and can provide official support services around for each of the CSI driver releases. Each Container Storage Provider has it's own requirements in terms of storage platform OS and may have other constraints not listed here.

Note

For Kubernetes 1.12 and earlier please see legacy FlexVolume drivers, do note that the FlexVolume drivers are being deprecated.

HPE CSI Driver for Kubernetes 2.4.1

Release highlights:

  • HPE Alletra Storage MP support
  • Kubernetes 1.29 support
  • Full KubeVirt, OpenShift Virtualization and SUSE Harvester support for HPE Alletra Storage MP, Alletra 9000, Primera and 3PAR
  • Full ARM64 support for HPE Alletra 5000/6000 and Nimble Storage
  • Support for foreign StorageClasses with the NFS Server Provisioner
  • SUSE Linux Enterprise Micro OS (SLE Micro) support

Upgrade considerations:

Kubernetes 1.26-1.291
Helm Chart v2.4.1 on ArtifactHub
Operators v2.4.1 on OperatorHub
v2.4.1 via OpenShift console
Worker OS Red Hat Enterprise Linux2 7.x, 8.x, 9.x, Red Hat CoreOS 4.12-4.15
Ubuntu 16.04, 18.04, 20.04, 22.04
SUSE Linux Enterprise Server 15 SP3, SP4, SP5 and SLE Micro4 equivalents
Platforms3 Alletra Storage MP5 10.2.x - 10.3.x
Alletra OS 9000 9.3.x - 9.5.x
Alletra OS 5000/6000 6.0.0.x - 6.1.2.x
Nimble OS 5.0.10.x, 5.2.1.x, 6.0.0.x, 6.1.2.x
Primera OS 4.3.x - 4.5.x
3PAR OS 3.3.x
Data protocols Fibre Channel, iSCSI
Filesystems XFS, ext3/ext4, btrfs, NFSv4*
Release notes v2.4.1 on GitHub
Blogs Introducing HPE Alletra Storage MP to HPE CSI Driver for Kubernetes

* = The HPE CSI Driver for Kubernetes is a block storage driver primarily. It includes an NFS Server Provisioner that allows "ReadWriteMany" PersistentVolumeClaims.
1 = For HPE Ezmeral Runtime Enterprise, SUSE Rancher, Mirantis Kubernetes Engine and others; Kubernetes clusters must be deployed within the currently supported range of "Worker OS" platforms listed in the above table. See partner ecosystems for other variations. Lowest tested and known working version is Kubernetes 1.21.
2 = The HPE CSI Driver will recognize CentOS, AlmaLinux and Rocky Linux as RHEL derives and they are supported by HPE.
3 = Learn about each data platform's team support commitment.
4 = SLE Micro nodes may need to be conformed manually, run transactional-update -n pkg install multipath-tools open-iscsi nfs-client sg3_utils and reboot if the CSI node driver doesn't start.
5 = The HPE CSI Driver for Kubernetes only support HPE Alletra Storage MP when used with HPE GreenLake for Block Storage. Please see the VAST CSI Driver for HPE GreenLake for File Storage.

HPE CSI Driver for Kubernetes 2.4.0

Release highlights:

  • Kubernetes 1.27 and 1.28 support
  • KubeVirt and OpenShift Virtualization support for Nimble/Alletra 5000/6000
  • Enhanced scheduling for the NFS Server Provisioner
  • Multiarch images (Linux ARM64/AMD64) for the CSI driver components and Alletra 9000 CSP
  • Major updates to SIG Storage images

Upgrade considerations:

Kubernetes 1.25-1.281
Helm Chart v2.4.0 on ArtifactHub
Operators v2.4.0 on OperatorHub
v2.4.0 via OpenShift console
Worker OS RHEL2 7.x, 8.x, 9.x, RHCOS 4.12-4.14
Ubuntu 16.04, 18.04, 20.04, 22.04
SLES 15 SP3, SP4, SP5
Platforms3 Alletra OS 9000 9.3.x - 9.5.x
Alletra OS 5000/6000 6.0.0.x - 6.1.1.x
Nimble OS 5.0.10.x, 5.2.1.x, 6.0.0.x, 6.1.2.x
Primera OS 4.3.x - 4.5.x
3PAR OS 3.3.x
Data protocols Fibre Channel, iSCSI
Filesystems XFS, ext3/ext4, btrfs, NFSv4*
Release notes v2.4.0 on GitHub
Blogs Introduction to new workload paradigms with HPE CSI Driver for Kubernetes

* = The HPE CSI Driver for Kubernetes is a block storage driver primarily. It includes an NFS Server Provisioner that allows "ReadWriteMany" PersistentVolumeClaims.
1 = For HPE Ezmeral Runtime Enterprise, SUSE Rancher, Mirantis Kubernetes Engine and others; Kubernetes clusters must be deployed within the currently supported range of "Worker OS" platforms listed in the above table. See partner ecosystems for other variations. Lowest tested and known working version is Kubernetes 1.21.
2 = The HPE CSI Driver will recognize CentOS, AlmaLinux and Rocky Linux as RHEL derives and they are supported by HPE.
3 = Learn about each data platform's team support commitment.

HPE CSI Driver for Kubernetes 2.3.0

Release highlights:

  • Introducing HPE Alletra 5000
  • Security updates
  • Support for Kubernetes 1.25-1.26 and Red Hat OpenShift 4.11-4.12
  • Support for SLES 15 SP4, RHEL 9.1 and Ubuntu 22.04

Upgrade considerations:

Kubernetes 1.23-1.261
Helm Chart v2.3.0 on ArtifactHub
Operators v2.3.0 on OperatorHub
v2.3.0 via OpenShift console
Worker OS RHEL2 7.x, 8.x, 9.x, RHCOS 4.10-4.12
Ubuntu 16.04, 18.04, 20.04, 22.04
SLES 15 SP2, SP3, SP4
Platforms3 Alletra OS 5000/6000 6.0.0.x - 6.1.1.x
Alletra OS 9000 9.3.x - 9.5.x
Nimble OS 5.0.10.x, 5.2.1.x, 6.0.0.x, 6.1.1.x
Primera OS 4.3.x - 4.5.x
3PAR OS 3.3.x
Data protocol Fibre Channel, iSCSI
Release notes v2.3.0 on GitHub
Blogs Support and security updates for HPE CSI Driver for Kubernetes (release blog)

1 = For HPE Ezmeral Runtime Enterprise, SUSE Rancher, Mirantis Kubernetes Engine and others; Kubernetes clusters must be deployed within the currently supported range of "Worker OS" platforms listed in the above table. See partner ecosystems for other variations. Lowest tested and known working version is Kubernetes 1.21.
2 = The HPE CSI Driver will recognize CentOS, AlmaLinux and Rocky Linux as RHEL derives and they are supported by HPE. 3 = Learn about each data platform's team support commitment.

Release Archive

HPE currently supports up to three minor releases of the HPE CSI Driver for Kubernetes.

Known Limitations

  • Always check with the Kubernetes vendor distribution which CSI features are available for use and supported by the vendor.
  • When using Kubernetes in virtual machines on VMware vSphere, OpenStack or similiar, iSCSI is the only supported data protocol for the HPE CSI Driver when using block storage.
  • Ephemeral, transient or non-persistent Kubernetes nodes are not supported unless the /etc/hpe-storage directory persists across node upgrades or reboots. The path is relocatable using a custom Helm chart or deployment manifest by altering the mountPath parameter for the directory.
  • The CSI driver support a fixed number of volumes per node. Inspect the current limitation by running kubectl get csinodes -o yaml and inspect .spec.drivers.allocatable for "csi.hpe.com". The "count" element contains how many volumes the node can attach from the HPE CSI Driver (default is 100).
  • The HPE CSI Driver uses host networking for the node driver. Some CNIs have flaky implementations which prevents the CSI driver components to communicate properly. Especially notorious is Flannel on K3s. Use Calico if possible for the widest compatibility.
  • The NFS Server Provisioner and each of the CSPs have known limitations listed separately.
  • The HPE CSI Driver does not support access mode transformations. I.e, it's not possible to clone an "RWO" volume into an "RWX" volume or vice versa. See this note on how to work around this limitation with OpenShift Virtualization.

iSCSI CHAP Considerations

If iSCSI CHAP is being used in the environment, consider the following.

CSI driver 1.3.0 and Above

CHAP is now an optional part of the initial deployment of the driver with parameters passed to Helm or the Operator. For object definitions, the CHAP_USER and CHAP_PASSWORD needs to be supplied to the csi-node-driver. The CHAP username and secret is picked up in the hpenodeinfo Custom Resource Definition (CRD). The CSP is under contract to create the user if it doesn't exist on the backend.

CHAP is a good measure to prevent unauthorized access to iSCSI targets, it does not encrypt data on the wire. CHAP secrets should be at least twelve charcters in length.

CSI driver 1.2.1 and Below

In version 1.2.1 and below, the CSI driver did not support CHAP natively. CHAP must be enabled manually on the worker nodes before deploying the CSI driver on the cluster. This also needs to be applied to new worker nodes before they join the cluster.

Kubernetes Feature Gates

Different features mature at different rates. Refer to the official table of feature gates in the Kubernetes docs.

The following guidelines appliy to which feature gates got introduced as alphas for the corresponding version of Kubernetes. For example, ExpandCSIVolumes got introduced in 1.14 but is still an alpha in 1.15, hence you need to enable that feature gate in 1.15 as well if you want to use it.

Kubernetes 1.13

  • --allow-privileged flag must be set to true for the API server

Kubernetes 1.14

  • --allow-privileged flag must be set to true for the API server
  • --feature-gates=ExpandCSIVolumes=true,ExpandInUsePersistentVolumes=true feature gate flags must be set to true for both the API server and kubelet for resize support

Kubernetes 1.15

  • --allow-privileged flag must be set to true for the API server
  • --feature-gates=ExpandCSIVolumes=true,ExpandInUsePersistentVolumes=true feature gate flags must be set to true for both the API server and kubelet for resize support
  • --feature-gates=CSIInlineVolume=true feature gate flag must be set to true for both the API server and kubelet for pod inline volumes (Ephemeral Local Volumes) support
  • --feature-gates=VolumePVCDataSource=true feature gate flag must be set to true for both the API server and kubelet for Volume cloning support

Kubernetes 1.19

  • --feature-gates=GenericEphemeralVolume=true feature gate flags needs to be passed to api-server, scheduler, controller-manager and kubelet to enable Generic Ephemeral Volumes