All data stored in Calenso is backed up every 6 hours and stored on 3 different servers. If the main server fails, the data would still be securely stored on two other servers.

At regular intervals, the backup is also written to an offline hard disk which is not connected to the Internet.

If the server should fail for any reason, Calenso would be up and running on an alternative server within a few hours with up-to-date data.