[DOC] Enhance docs on snapshots for Cephfs drivers

[Victoria Martinez de la Cruz]

Ceph changed the way in which they managed snapshots and this can lead to some confusion with our users. We could add some docs clarifying this.

Something like the following in the Cephfs driver docs [0] would do

"Snapshots for new style subvolumes are created one level up in order to allow users to preserve subvolume snapshots even after a subvolume is deleted. E.g. Given a volume 63fe53b8-1bc3-4b07-a39b-5f80cc68cb85 and a subvolume d2ff8c56-4232-4dc2-a80d-25681205bde3, /volumes/_nogroup/63fe53b8-1bc3-4b07-a39b-5f80cc68cb85/.snap contains all the snapshots for the subvolume. Actual data for the subvolume is in /volumes/_nogroup/63fe53b8-1bc3-4b07-a39b-5f80cc68cb85/d2ff8c56-4232-4dc2-a80d-25681205bde3/. The users need to clone the subvolume snapshot data to use it".

[0] https://docs.openstack.org/manila/latest/admin/cephfs_driver.html

[Vida Haririan (vhariria)]

Additional comments at https://meetings.opendev.org/meetings/manila/2022/manila.2022-11-10-15.00.log.html

[Clifford Emeka (emclidon)]

Hello Carlos Can I still take on this bug if it's still open?

[Goutham Pacha Ravi (gouthamr)]

> Hello Carlos Can I still take on this bug if it's still open?

Hi Clifford,

Yes. I've assigned the bug to you. Please go ahead..

[Solomon Barine Akpuru (solly47)]

Hello Goutham, I would like to work on this bug.