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About Persistent Volume Support
Persistent Volume Claims (PVCs) are requests for storage resources in your cluster. By default, container images have an ephemeral file system. In order for containers to persist files beyond the lifetime of the container, a can be created to obtain a persistent volume which the container can mount and read/write files. In , are backed by Ceph.
Management and customization tasks for Kubernetes can be accomplished
by using StorageClasses set up by two Helm charts;
rbd-provisioner and cephfs-provisioner. The
rbd-provisioner, and cephfs-provisioner Helm
charts are included in the platform-integ-apps system
application, which is automatically loaded and applied when Ceph is
configured.
If platform-integ-apps is not applied, then enable Ceph.
Enabling Ceph would automatically apply the
platform-integ-apps application. For information on how to
enable Ceph, see Ceph Cluster on a Controller Host
<ceph-cluster-on-a-controller-host>.
are supported with the following options:
- with accessMode of ReadWriteOnce backed by Ceph
- only one container can attach to these
- management and customization tasks related to these PVCs are done
through the
rbd-provisionerHelm chart provided byplatform-integ-apps
- with accessMode of ReadWriteMany backed by CephFS
- multiple containers can attach to these PVCs
- management and customization tasks related to these are done through
the
cephfs-provisionerHelm chart provided byplatform-integ-apps
After platform-integ-apps is applied the following
system configurations are created:
Ceph Pools
~(keystone_admin)]$ ceph osd lspools kube-rbd kube-cephfs-data kube-cephfs-metadataCephFS
~(keystone_admin)]$ ceph fs ls name: kube-cephfs, metadata pool: kube-cephfs-metadata, data pools: [kube-cephfs-data ]Kubernetes StorageClasses
~(keystone_admin)]$ kubectl get sc NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION cephfs cephfs.csi.ceph.com Delete Immediate true general (default) rbd.csi.ceph.com Delete Immediate true