Please describe the problem.

Without checking the manpage, I did:

cd usb-drive-1/annex
git annex sync --content --fast usb-drive-2

I thought, that ┬┤--fast┬┤ would mean the same thing as in git-annex-copy:

When copying content to a remote, avoid a round trip to check if the remote already has content. This can be faster, but might skip copying content to the remote in some cases.

Only here with git-annex-sync, --fast means:

Only sync with the remotes with the lowest annex-cost value configured

This is sub-optimal UI and this ship has sailed. But the command should have failed because it does not make sense to specify both --fast and a REMOTE, does it?

I only noticed after a while that annex was syncing to remote at ~/annex and filling my laptops hard disk.

I actually used --fast because I was annoyed by annex iterating over all files in the repo during the sync, which for some reason it doesn't do when syncing with an SSH remote.

What version of git-annex are you using? On what operating system?

8.20200330, Debian testing

fixed --Joey