Re: How to exclude other filesystems but include subvolumes?

[Nicholas D Steeves <nsteeves@gmail.com>]

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Hi,

Ulli Horlacher <framstag@rus.uni-stuttgart.de> writes:

> Many programs like find, tar, rsync, cp, du, etc have options to exclude
> other filesystems, eg rsync: 
>   --one-file-system, -x    don't cross filesystem boundaries
>
> But this also excludes subvolumes, which are in the same filesystem.

Yes, because subvolumes are boundaries.

> How can I address a btrfs filesystem with all subvolumes, but exclude
> other filesystems?
>
> Example: I want to copy the / filesystem (with all subvolumes), what is the
> best solution (for scripting!)?

The best solution that I've found is to 'mount -o subvolid=5
$your_root_device /somewhere' (I think /btrfs-admin or /.btrfs-admin is
logical), where only the root user and the sudo group can read the
mountpoint, and only root can write to it.  I suspect you'll agree that
it's important to include the output of 'btrfs sub list -pta
$subvolid_5_mountpoint' in that backup (for use by humans) as well in
JSON format if you want to someday automate restoration of the subvolume
structure.  Ie:

  1. Mount a top-level view.
  2. List the subvolume structure and insure it ends up in you
  replicant.
  2.5: Optionally recreate the subvolume structure at the target.
  3. Replicate everything in one shot, without '--one-file-system, -x'.

Best,
Nicholas

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