Specify -X when backing up oCIS using rsync

Hello community,
I would like to quickly tell the inexperienced user (maby running oCIS on a Raspberry Pi with Docker like I do) that in order to back up oCIS using rsync, one needs to specify the -X option in addition to the -a option so: rsync -aX of ocis-config and ocis-data produces a viable backup that can be mounted with the docker image.
It might be obvious to the professional, but the time it took me to figure this out was rediculous. Eventually, I learned that cp -a would work, but rsync -a would not, so I could look at the differences between the two commands.
-X is also not pre-configured in rsnapshot, which I use for my backups.
Maybe this can be of help to somebody. If there is more to keep in mind in order to back up oCIS, I would be very happy to learn.