Re: btrfs snapshots (of root file system)?

[hw <hw@adminart.net>]

On Sun, 2023-10-01 at 10:51 +0100, debian-user@howorth.org.uk wrote:
> hw <hw@adminart.net> wrote:
> > Hi,
> > 
> > with btrfs, how do I make a snapshot of the root file system?  The
> > purpose is to update software and being able to go back to a previous
> > state if necessary.
> > 
> > There doesn't seem to be a command to create snapshots but only
> > subvolumes?  How does a subvolume turn into a snapshot?  (The root
> > file system is, of course, not on a subvolume.)
> > 
> > How do I merge snapshots?  IIRC, when you remove a ZFS snapshot, the
> > older state is merged to the state the snapshot is in.  Apparently
> > btrfs can only delete snapshots --- and it seems like a bad idea to
> > delete the root file system.  How would I boot from it when it's been
> > deleted?
> > 
> > Can I make a snapshot on a different volume?  The manpage doesn't say
> > that the destination of a subvolume must be on the same volume, and in
> > any case, I should be able to do that.
> 
> google says:

Thanks!  It still doesn't make much sense ...