or is that a bug?
or am I doing something wrong?
It is always incremental and we have many unit and functional tests around this area so there shouldn’t be any bugs. You will need to provide a lot more information for me to help out any further. In particular the backup.log file would be a good place to start looking. I’d recommend you file a bug at issues.couchbase.com and include that log file as well as information about your os, cluster configuration and any other details you think might be useful to help figure out what is going on.
If you are an enterprise customer (since cbbackupmgr is an enterprise binary) I would recommend you contact support since they will be able to help you out immediately. If you’re evaluating Couchbase Enterprise Edition then you should be able to get some help with your evaluation by contact our sales team.