Kopia is the hardest tool to setup from all the tools considered here. This starts with initializing a backup storage: All tools except JMBB need this step before performing the first backup whereas JMBB asks the user interactively for the password upon first backup but otherwise does not need to do any setup. Kopia, however, requires three setup steps:

1. Creation of a “repository”
2. Connecting to the repository
3. Configuration of a backup policy

The second step may stem from the fact that Kopia supports multiple different target storages that may require a dedicated and specific login procedure of sorts. The backup policy thing is quite unintuitive though: Kopia has “global” and target-specific policies where things not configured in the target-specific one can be inherited from the “global” ones. Also, the default policy includes that files listed in .kopiaignore files are ignored opening up a simple attack surface where a malware would just add all of the user’s files to hidden .kopiaignore files tricking the user into believing that data is backed up while it is in fact ignored. To some extent, this is my point of view that backup excludes should be minimal as not to confuse the user about which files are backed up and which not. Of course, .kopiaignore is also a useful feature to allow ignoring certain files that do not need to be backed up with exceptionally fine granularity.