[ceph-users] cephfs manila snapshots best practices

Dan van der Ster dan at vanderster.com
Thu Mar 21 08:15:35 PDT 2019

On Thu, Mar 21, 2019 at 1:50 PM Tom Barron <tbarron at redhat.com> wrote:
> On 20/03/19 16:33 +0100, Dan van der Ster wrote:
> >Hi all,
> >
> >We're currently upgrading our cephfs (managed by OpenStack Manila)
> >clusters to Mimic, and want to start enabling snapshots of the file
> >shares.
> >There are different ways to approach this, and I hope someone can
> >share their experiences with:
> >
> >1. Do you give users the 's' flag in their cap, so that they can
> >create snapshots themselves? We're currently planning *not* to do this
> >-- we'll create snapshots for the users.
> >2. We want to create periodic snaps for all cephfs volumes. I can see
> >pros/cons to creating the snapshots in /volumes/.snap or in
> >/volumes/_nogroup/<uuid>/.snap. Any experience there? Or maybe even
> >just an fs-wide snap in /.snap is the best approach ?
> >3. I found this simple cephfs-snap script which should do the job:
> >http://images.45drives.com/ceph/cephfs/cephfs-snap  Does anyone have a
> >different recommendation?
> >
> >Thanks!
> >
> >Dan
> >_______________________________________________
> >ceph-users mailing list
> >ceph-users at lists.ceph.com
> >http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> Dan,
> Manila of course provides users with self-service file share snapshot
> capability with quota control of the snapshots.  I'm sure you are
> aware of this but just wanted to get it on record in this thread.
> Snapshots are not enabled by default for cephfs native or cephfs with
> nfs in Manila because cephfs snapshots were experimental when the
> cephfs driver was added and we maintain backwards compatability in
> the Manila configuration.  To enable, one sets:
>    cephfs_enable_snapshots = True
> in the configuration stanza for cephfsnative or cephfsnfs back end.
> Also, the ``share_type`` referenced when creating shares (either
> explicitly or the default one) needs to have the snapshot_support
> capability enabled -- e.g. the cloud admin would (one time) issue a
> command like the following:
>   $ manila type-key <default-share-type> set snapshot_support=True
> With this approach either the user or the administrator can create
> snapshots of file shares.
> Dan, I expect you have your reasons for choosing to control snapshots
> via a script that calls cephfs-snap directly rather than using Manila
> -- and of course that's fine -- but if you'd share them it will help
> us Manila developers consider whether there are use cases that we are
> not currently addressing that we should consider.

Hi Tom, Thanks for the detailed response.
The majority of our users are coming from ZFS/NFS Filers, where
they've gotten used to zfs-auto-snapshots, which we create for them
periodically with some retention. So accidental deletions or
overwrites are never a problem because they can quickly access
yesterday's files.
So our initial idea was to replicate this with CephFS/Manila.
I hadn't thought of using the Manila managed snapshots for these
auto-snaps -- it is indeed another option. Have you already considered
Manila-managed auto-snapshots?

Otherwise, I wonder if CephFS would work well with both the fs-wide
auto-snaps *and* user-managed Manila snapshots. Has anyone tried such
a thing?



> Thanks,
> -- Tom Barron

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