I have two hard disks on two machines, connected remotely. I would like to start using the promising btrfs send/receive feature to speed up the incremental backup I take over the net, instead of rsync.
On the backup side I already have a backup copy of almost all the data (about 1TB). I did a lot of search, but every article I found starts sending all the data to the new location to bootstrap the incremental backup scheme. 1TB is a lot of data to transmit on the internet and btrfs send/receive can't resume if something goes wrong, as far as I understood. I could store the huge stream in a file and send it with rsync, but what if I don't have a spare 1TB to store the temporary stream file (on each side...)?
Now the question is: can you someway reuse already existing data on the backup side to start using the send/receive feature of btrfs OR a first send of ALL the data must be executed in any case?