================ CephFS Snapshots

CephFS snapshots create an immutable view of the file system at the point in time they are taken. CephFS snapshots are managed in a special hidden subdirectory named .snap. Snapshots are created using mkdir inside the .snap directory.

Snapshots can be exposed with different names by changing the following client configurations:

snapdirname which is a mount option for kernel clients
client_snapdir which is a mount option for ceph-fuse.

Snapshot Creation

The CephFS snapshot feature is enabled by default on new file systems. To enable the CephFS snapshot feature on existing file systems, use the command below.

.. code-block:: bash

$ ceph fs set <fs_name> allow_new_snaps true

When snapshots are enabled, all directories in CephFS will have a special .snap directory. (You may configure a different name with the client's snapdir setting if you wish.) To create a CephFS snapshot, create a subdirectory under .snap with a name of your choice. For example, to create a snapshot on directory /file1/, run the command mkdir /file1/.snap/snapshot-name:

.. code-block:: bash

$ touch file1
$ cd .snap
$ mkdir my_snapshot

Using Snapshots to Recover Data

Snapshots can also be used to recover deleted files:

create a file1 and create snapshot snap1

.. code-block:: bash

$ touch /mnt/cephfs/file1
$ cd .snap
$ mkdir snap1

create a file2 and create snapshot snap2

.. code-block:: bash

$ touch /mnt/cephfs/file2
$ cd .snap
$ mkdir snap2

delete file1 and create a new snapshot snap3

.. code-block:: bash

$ rm /mnt/cephfs/file1
$ cd .snap
$ mkdir snap3

recover file1 using snapshot snap2 using cp command

.. code-block:: bash

$ cd .snap
$ cd snap2
$ cp file1 /mnt/cephfs/

Snapshot Deletion

Snapshots are deleted by running rmdir on the .snap directory that they are rooted in. (Attempts to delete a directory that roots the snapshots will fail. You must delete the snapshots first.)

.. code-block:: bash

$ cd .snap
$ rmdir my_snapshot