On 2015-01-06 23:11, Jérôme Poulin wrote:
> On Mon, Jan 5, 2015 at 6:59 AM, Austin S Hemmelgarn
> <ahferroin7@gmail.com> wrote:
>> Secondly, I would highly recommend not using ANY non-cluster-aware FS on top
>> of a clustered block device like RBD
>
>
> For my use-case, this is just a single server using the RBD device. No
> clustering involved on the BTRFS side of thing.
My only point is that there isn't anything in BTRFS to handle it 
accidentally being multiply mounted.  Ext* for example aren't clustered, 
but do have an optional feature to prevent multiple mounting.
> However, it was really useful to take snapshots (just like LVM) before modifying the
> filesystem in any way.
>
Have you tried Ceph's built in snapshot support?  I don't remember how 
to use it, but I do know it is there (at least, it is in the most recent 
versions), and it is a bit more like LVM's snapshots than BTRFS is.