On Sun, Jan 10, 2021 at 01:06:44PM +0000, Graham Cobb wrote: > On 10/01/2021 07:41, cedric.dew...@eclipso.eu wrote: > > I've tested some more. > > > > Repeatedly sending the difference between two consecutive snapshots creates > > a structure on the target drive where all the snapshots share data. So 10 > > snapshots of 10 files of 100MB takes up 1GB, as expected. > > > > Repeatedly sending the difference between the first snapshot and each next > > snapshot creates a structure on the target drive where the snapshots are > > independent, so they don't share any data. How can that be avoided? > > If you send a snapshot B with a parent A, any files not present in A > will be created in the copy of B. The fact that you already happen to > have a copy of the files somewhere else on the target is not known to > either the sender or the receiver - how would it be? > > If you want the send process to take into account *other* snapshots that > have previously been sent, you need to tell send to also use those > snapshots as clone sources. That is what the -c option is for.
And even then, it won't spot files that are identical but which don't share extents. > Alternatively, use a deduper on the destination after the receive has > finished and let it work out what can be shared. This is a viable approach. Hugo. -- Hugo Mills | The last man on Earth sat in a room. Suddenly, there hugo@... carfax.org.uk | was a knock at the door. http://carfax.org.uk/ | PGP: E2AB1DE4 | Frederic Brown
