FilesystemSubVolumeGroup CRD

Rook allows creation of Ceph Filesystem SubVolumeGroups through the custom resource definitions (CRDs). Filesystem subvolume groups are an abstraction for a directory level higher than Filesystem subvolumes to effect policies (e.g., File layouts) across a set of subvolumes. For more information about CephFS volume, subvolumegroup and subvolume refer to the Ceph docs.

Creating daemon¶

To get you started, here is a simple example of a CRD to create a subvolumegroup on the CephFilesystem "myfs".

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apiVersion: ceph.rook.io/v1
kind: CephFilesystemSubVolumeGroup
metadata:
  name: group-a
  namespace: rook-ceph # namespace:cluster
spec:
  # The name of the subvolume group. If not set, the default is the name of the subvolumeGroup CR.
  name: csi
  # filesystemName is the metadata name of the CephFilesystem CR where the subvolume group will be created
  filesystemName: myfs
  # reference https://docs.ceph.com/en/latest/cephfs/fs-volumes/#pinning-subvolumes-and-subvolume-groups
  # only one out of (export, distributed, random) can be set at a time
  # by default pinning is set with value: distributed=1
  # for disabling default values set (distributed=0)
  pinning:
    distributed: 1            # distributed=<0, 1> (disabled=0)
    # export:                 # export=<0-256> (disabled=-1)
    # random:                 # random=[0.0, 1.0](disabled=0.0)
  # Quota size of the subvolume group.
  #quota: 10G
  # data pool name for the subvolume group layout instead of the default data pool.
  #dataPoolName: myfs-replicated

Settings¶

If any setting is unspecified, a suitable default will be used automatically.

CephFilesystemSubVolumeGroup metadata¶

• name: The name that will be used for the Ceph Filesystem subvolume group.

CephFilesystemSubVolumeGroup spec¶

• name: The spec name that will be used for the Ceph Filesystem subvolume group if not set metadata name will be used.

• filesystemName: The metadata name of the CephFilesystem CR where the subvolume group will be created.

• quota: Quota size of the Ceph Filesystem subvolume group.

• dataPoolName: The data pool name for the subvolume group layout instead of the default data pool.

• pinning: To distribute load across MDS ranks in predictable and stable ways. See the Ceph doc for Pinning subvolume groups.

  • distributed: Range: <0, 1>, for disabling it set to 0
  • export: Range: <0-256>, for disabling it set to -1
  • random: Range: [0.0, 1.0], for disabling it set to 0.0

Create a storage class for the subvolume group¶

• Create a CephFilesystem CR
• Create a CephFilesystemSubvolumegroup CR

Note The clusterID can be explicitly set in the spec of the CephFilesystemSubVolumeGroup CR. If it is not set, Rook will auto-generate the clusterID.

• Extract the clusterID from the status of the CephFilesystemSubvolumegroup CR:

  1 2	$ kubectl -n rook-ceph get cephfilesystemsubvolumegroup <name> -o jsonpath="{.status.info.clusterID}" 80fc4f4bacc064be641633e6ed25ba7e

This returns spec.clusterID if present, otherwise falls back to the auto generated one.

• Set the clusterID in the StorageClass, VolumeSnapshotClass, and VolumeGroupSnapshotClass to this value instead of the name of the cluster namespace