Re: reorganizing my snapshots: how to move a readonly snapshot? (btrbk)

[Dave T <davestechshop@gmail.com>]

On Tue, Jul 27, 2021 at 1:34 PM Graham Cobb <g.btrfs@cobb.uk.net> wrote:
>
>
> On 27/07/2021 17:47, Dave T wrote:
> > I'm using btrbk to create regular snapshots. I see a way I can improve
> > the organization of my snapshots now that I have more experience with
> > this tool, but it requires moving existing snapshots to a different
> > directory.
> >
> > I would prefer to avoid re-creating the full initial snapshot in the
> > new location and I would prefer to avoid losing the existing
> > incremental snapshots. I also want to preserve the existing parent
> > relationships used by my snapshot tools (mainly btrbk).
> >
> > I'm thinking about using the solution mentioned here:
> > https://unix.stackexchange.com/a/149933
> >
> >> To set a snapshot to read-write, you do something like this:
> >> btrfs property set -ts /path/to/snapshot ro false
> >
> > My plan would be to change the ro property to false, move the
> > snapshots, reset the ro property to true, and change my btrbk.conf to
> > match the new path.
> >
> > What are the caveats in this plan?
>
> I believe that setting snapshots read-write and then back to ro is not
> recommended and is unsupported.

I have heard something vague about that before, which is why I asked
before doing it. It still seems unclear, but I'll avoid that approach
unless someone confirms it is OK.

> It may work but I am sure I have seen
> reports of problems with send/receive when snapshots have been made rw,
> changed and then set ro again.
>
> I recommend using the btrbk archive feature to move your existing
> snapshots and then start building on top of those. I think I did exactly
> this a long time ago when I was in a similar position of wanting to move
> my btrbk setup.

Thank you for the idea. The archive feature is the one btrbk feature I
have not explore yet. It looks simple to use. btrbk is a nice tool.

>
> Graham