Persistent Storage

Introduction

cegedim.cloud now provides a multi-tenants Ceph Storage Platform as a CSI provider with the following specifications:

• Data is replicated 4 times and is evenly distributed (using Ceph Crush Map) across 2 Datacenters to ensure that under disaster scenarios, 2 replicas of data are always available.

• Each Kubernetes cluster, as a Ceph client, has its own pool of data on Ceph server and consumes services with its own pool scoped credential.

• Only CSI Ceph RBD is provided for the moment.

Further information on Ceph CSI can be found here:

Welcome to Ceph — Ceph Documentation

Versions

Component	Version
Ceph Cluster	17.2.5
CSI Ceph	3.9.0

Storage Class

Name	Description
cgdm-rwo	use CSI Ceph rbd to provision ReadWriteOnce persistent volumes

High Availability

	EB	ET
Replication	x4	x4
Fault Tolerance: 1 AZ is DOWN	✅	✅
Fault Tolerance: 1 DC is DOWN	✅	✅

CSI features

	CSI ceph-rbd
Provisioning new PV	✅
Remount existing PV	✅
Compatible with all K8S applications	✅
Multi-mount (RWX)	❌
Resizable	✅
Snapshot	✅
Fault Tolerance: loss of 1 AZ	✅
Fault Tolerance: loss of 1 DC	✅
Compatible with K8S 1.22+	✅
Compatible with K8S 1.22-	✅

Snapshot and Restore PVC in Kubernetes

cegedim.cloud uses External Snapshotter to snapshot & restore PVC of your Kubernetes clusters.

All information about this application can be found here:

GitHub - kubernetes-csi/external-snapshotter: Sidecar container that watches Kubernetes Snapshot CRD objects and triggers CreateSnapshot/DeleteSnapshot against a CSI endpoint.GitHub

How to know if I have active snapshotclass on my cluster

We recommend to name the snapshotclass after the storageclass as a best practice. Simply execute the below command to check:

$ kubectl get sc
NAME                 PROVISIONER           RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
cgdm-rwo (default)   rbd.csi.ceph.com      Delete          Immediate           true                   57d

$ kubectl get  volumesnapshotclass
NAME       DRIVER                DELETIONPOLICY   AGE
cgdm-rwo   rbd.csi.ceph.com      Delete           36d

How to list available CSI in my cluster

To list all CSI available in a Kubernetes cluster, perform the following:

$ kubectl get sc
NAME                  PROVISIONER              RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
cgdm-rwo (default)    rbd.csi.ceph.com         Delete          Immediate              true                   42d

Here is a mapping between Storage Class and CSI:

Storage Classes	CSI
cgdm-rwo	Ceph RBD