Partial revisions for long backups

Hi all!

I have slow and flaky internet (thanks Comcast) so large backups can take several days. This makes the probablitiy of interrupted backups very likely.

Unfortunately I also have slow and low-powered NAS machines where chunking/hashing takes a significant time, even if the data has already been backed up and all chunks exist in the destination.

This combination makes it very difficult to finish large backups or even make any progress before the next internet interruption.

It would be really great if Duplicacy could upload a partial revision, containing only the as-of-yet backed-up files at some configurable interval (default perhaps 1 hour). This would allow an interrupted backup to continue at the last partial revision.


Extra details:

I was running a long backup on a Windows machine when suddenly the -vss shadow copy disappeared. This made the backup finish early and contain only the as-of-yet backed up files. The next backup happily continued from the partial revision and I saved a lot of hashing time.

A feature with the exact same behavior seems like it would address my issue.

If I’m not mistaken, such a feature could also alleviate the issue of a prune removing blocks for a backup lasting longer than 1 week.

Extra extra details:

What I have to do now is exclude subfolders of my backup, finish a backup, then remove exclusions one at a time. If a folder is too large to finish in one backup, I then have to manually recurse into that folder and repeat the exclusion process.