Am 17.07.2019 um 01:24 schrieb Ulli Horlacher: > How do I know that /mnt/tmp/ss is a snapshot? > I cannot see a snapshot identifier.
>From the btrfs-subvolume man page: > A snapshot is a subvolume like any other, with given initial content. By default, snapshots are created > read-write. File modifications in a snapshot do not affect the files in the original subvolume. I believe the usual practice is to create snapshots with the -r flag and follow some naming convention (e.g. place them in a common .snapshots folder named by date), but you're free to switch between read-only and read-write mode for a snapshot at any time using the btrfs property command. That allows for some intereresting feats: e.g. there's no guarantee that a (now) read-only snapshot actually reflects the source's state at creation time (if someone modified it and re-applied the ro flag). On the other hand, reverting to a snapshotted state may be as easy as making the snapshot rw and changing the mount options to use it's subvolid - no need to copy any files back and forth. If there is a specific reason why you want to discern snapshots from other subvolumes (verification/auditing/forensics?), maybe you can get help here by elaborating further on that. Bernhard Kühnel
