Hello James, The special thing about subvolumes is that you can only take snapshots at their root but not inside. This is a security feature: give a subdirectory of a subvolume to a user, set the quota on the subvolume, and you can be sure that the user will not be able to circumvent the quota by creating new snapshots in the area he has access to. On Fri, Jun 20, 2025 at 3:54 PM James Tocknell <james.tocknell@mq.edu.au> wrote:
Hi All
Possibly a dumb question, but given with cephfs you can apply quotas to arbitrary directories, snapshot arbitrary directories, assign arbitrary directories to pools etc. what is special/different about subvolumes, and why would I want to use them (and more importantly, not want to use them)? I guess the only thing I can see could be around where the extended attributes are assigned (with the two-level directory structure enabling setting a quota while not allowing read access to the directory above, based on looking at the cephfs CSI?), but I feel I'm missing something obvious.
The specific usecase I'm looking at is evaluating using just quotas vs subvolumes for team shares (to ensure that each team only uses the amount of storage they require), but in general I'm trying to understand subvolumes.
Regards James _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
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