The Document Database Service now supports Backup Encryption. For all existing instances created with Disk Encryption, an encrypted backup is now created for any type of manual or automatic backup task. With the automatic backup, nothing must be done at this point, the encryption takes place automatically.
To use this functionality an instance must be created with Disk Encryption or an existing instance has already been created by selecting Disk Encryption.
Subsequent activation of Disk Encryption after creating a Document Database Service instance is not possible.
Further information can be found in the DDM area of the Help Center.