Re: back&forth send/receiving?

[Andrei Borzenkov <arvidjaar@gmail.com>]

On 17.02.2023 20:12, Christoph Anton Mitterer wrote:
> ~/mnt/master# btrfs send snap-1 | /usr/bin/time -v btrfs receive ~/mnt/copy1/
> ~/mnt/master# btrfs send snap-1 | /usr/bin/time -v btrfs receive ~/mnt/copy2/
> ~/mnt/master# btrfs subvolume snapshot -r data/ snap-2
> Create a readonly snapshot of 'data/' in './snap-2'
> ~/mnt/master# btrfs send -p snap-1 snap-2 | /usr/bin/time -v btrfs receive ~/mnt/copy1/
> ~/mnt/master# btrfs send -p snap-1 snap-2 | /usr/bin/time -v btrfs receive ~/mnt/copy2/

So copy1 and copy2 are identical. This is not what you said earlier (at 
least, it is not how what you said earlier sounded).

Of course you can use either of them and continue incremental chain on 
another.
...
> 
> They may or may not be.
> Sometimes, I just send the same snapshot (e.g. from some specific date)
> to all copyN ... sometimes the most recent one of all of them is
> different.
> 

So are all copyN identical or not?

> But I always keep on (old) master the snapshot that are most recent on
> each of copyN, so that I can continue from there, when I do the next
> round of snapshot.
> 

It does not matter what you keep on old master because old master is 
gone. What matter is what you keep on each copyN.