Hi everyone,

I'm interested in using Borg to backup my webserver to an Amazon S3 bucket. I've been using Duplicity, but I'm sick of the full/incremental model, as well as the difficulty of pruning backups. I love the ease of use and features that Borg provides, but I don't really understand the internals and I'm not sure if it will work with Amazon S3 storage.

Specifically, I'm considering mounting my S3 bucket over FUSE, using one of the following three options:

• https://github.com/s3fs-fuse/s3fs-fuse/wiki/Fuse-Over-Amazon
• https://github.com/archiecobbs/s3backer
• https://github.com/danilop/yas3fs/wiki

Any comments on which, if any would be more appropriate? And how tolerant would Borg be to S3's "eventual consistency" weirdness?

Additionally, I need to plan against the worst-case scenario of a hacker getting root access to my server and deleting the backups on S3 using the stored credentials on my server. To eliminate this possibility, I was thinking about enabling S3 versioning on the bucket so that files deleted with my server's S3 user account can still be recovered via my main Amazon user account. Then, I would have S3 lifecycle management configured to delete all versions of deleted files after X amount of time. In this case,

• How much of my S3 data would Borg routinely need to download in order to figure out which files have changed and need to be backup up? (I'm worried about bandwidth costs.)
• How much accumulated clutter and wasted space could I expect from files that Borg "deletes", (which will actually be retained on S3 due to the versioning)?

Again, my concerns are based on me not really understanding all the black magic that happens with all the chunks and indexes inside a Borg repository, and how much they change from one backup to the next.

Thanks in advance for the help!

💰 there is a bounty for this