Replication

Dell Container Storage Modules (CSM) for Replication

Container Storage Modules (CSM) for Replication is part of the open-source suite of Kubernetes storage enablers for Dell products.

CSM for Replication project aims to bring Replication & Disaster Recovery capabilities of Dell Storage Arrays to Kubernetes clusters. It helps you replicate groups of volumes using the native replication technology available on the storage array and can provide you a way to restart applications in case of both planned and unplanned migration.

CSM for Replication Capabilities

CSM for Replication provides the following capabilities:

Capability PowerMax PowerStore PowerScale PowerFlex Unity
Replicate data using native storage array based replication yes yes yes yes no
Asynchronous file volume replication no no yes no no
Asynchronous block volume replication yes yes n/a yes no
Synchronous file volume replication no no no no no
Synchronous block volume replication yes no n/a no no
Active-Active (Metro) block volume replication yes no n/a no no
Active-Active (Metro) file volume replication no no no no no
Create PersistentVolume objects in the cluster representing the replicated volume yes yes yes yes no
Create DellCSIReplicationGroup objects in the cluster yes yes yes yes no
Failover & Reprotect applications using the replicated volumes yes yes yes yes no
Online Volume Expansion for replicated volumes yes no no yes no
Provides a command line utility - repctl for configuring & managing replication related resources across multiple clusters yes yes yes yes no

Supported Operating Systems/Container Orchestrator Platforms

COP/OS PowerMax PowerStore PowerScale PowerFlex
Kubernetes 1.26, 1.27, 1.28 1.26, 1.27, 1.28 1.26, 1.27, 1.28 1.26, 1.27, 1.28
Red Hat OpenShift 4.13, 4.14 4.13, 4.14 4.13, 4.14 4.13, 4.14

Supported Storage Platforms

PowerMax PowerStore PowerScale PowerFlex
Storage Array PowerMax 2500/8500 PowerMaxOS 10 (6079) , PowerMaxOS 10.0.1 (6079) , PowerMaxOS 10.1 (6079)
PowerMax 2000/8000 - 5978.711.xxx, 5978.479.xxx
Unisphere 10.0,10.0.1,10.1		 3.0, 3.2, 3.5 OneFS 9.3, 9.4, 9.5.0.x (x >= 5) 3.6.x, 4.0.x, 4.5

Note: File Replication for PowerMax is currently not supported

Details

As on the storage arrays, all replication related Kubernetes entities are required/created in pairs -

  1. Pair of Kubernetes Clusters
  2. Pair of replication enabled Storage classes
  3. Pair of PersistentVolumes representing the replicated pair on the storage array
  4. Pair of DellCSIReplicationGroup objects representing the replicated protection groups on the storage array

You can also use a single stretched Kubernetes cluster for protecting your applications. Even in this topology, rest of the objects still exist in pairs.

What it does not do

  • Replicate application manifests within/across clusters.
  • Stop applications before the planned/unplanned migration.
  • Start applications after the migration.
  • Replicate PersistentVolumeClaim objects within/across clusters.
  • Replication with METRO mode does not need Replicator sidecar and common controller.
  • Different namespaces cannot share the same RDF group for creating volumes with ASYNC mode for PowerMax.
  • Same RDF group cannot be shared across different replication modes for PowerMax.
  • Replication support for multiple drivers installed on same Kubernetes cluster.

QuickStart

  1. Install all required components:
  • Enable replication during CSI driver installation
  • Install CSM Replication Controller & repctl
  1. Create replication enabled storage classes
  2. Create PersistentVolumeClaim using the replication enabled storage class

How it works

At a high level, the following happens when you create a PersistentVolumeClaim object using a replication enabled storage class -

  1. CSI driver creates protection group on the storage array (if required)
  2. CSI driver creates the volume and adds it to the protection group. There will be a corresponding group and pair on the remote storage array
  3. A DellCSIReplicationGroup object is created in the cluster representing the protection group on the storage array
  4. A replica of the PersistentVolume & DellCSIReplicationGroup is created

You can refer this page for more details about the architecture.

Once the DellCSIReplicationGroup & PersistentVolume objects have been replicated across clusters (or within the same cluster), you can exercise the general Disaster Recovery workflows -

  1. Planned Migration to the target cluster/array
  2. Unplanned Migration to the target cluster/array
  3. Reprotect volumes at the target cluster/array
  4. Maintenance activities like - Suspend, Resume, Establish replication
Deployment

Installation for Dell Container Storage Module (CSM) for Replication

Architecture

High level architecture for CSM for Replication

Cluster Topologies

Supported Cluster Topologies with CSM Replication

Disaster Recovery

Disaster Recovery Workflows

High Availability

High Availability support for CSI PowerMax

Migration

Support for Array Migration of Volumes

Monitoring

DellCSIReplicationGroup Monitoring

Replication Actions

DellCSIReplicationGroup Actions

Volume Expansion

Online expansion of replicated volumes

Tools

repctl tool for Replication feature in detail

Troubleshooting

Troubleshooting guide

Release notes

Dell Container Storage Modules (CSM) release notes for replication

Upgrade

Upgrade guide

Uninstall

Dell Container Storage Modules (CSM) for Replication Uninstallation