Initialize S3 backups with USB drive

Hello everybody,

planning to regularly backup a fairly large data volume (~3TB) to a S3 storage local to me, I have been given a USB drive with said data in order to prepare an initial backup to the S3 repository.

After I have backed it up locally to the S3 repo, it was possible to see and browse the data from the remote server.

But the following, remote backup seems to copy everything over, although the file paths are the same.

What could be done to keep the initial backup as a base for remote backups?

Thank you for any answer.

There are two things: Scanning, reading, chunking the files on one side and encrypting and storing the chunks (called blobs) on the remote storage.

If you backup the same files from another host or directory, they will be still scanned, read, and chunked. But if the blobs already exist in the repository, they will not be saved again and this don’t need to be transferred to a remote repository.

So in your case the backups seems to copy things over, but will in fact only copy contents if files changed.

If you wanted to also skip the reading and chunking part (which can be also quite time-consuming), restic needs to find a fitting parent snapshot, i.e. you must use the same host name and same path to backup. The hostname can be set by the --host option, but about paths you have to mount the USB drive to the right dir. There is actually no support in restic to manually set or change paths.