Here is a manual backup of Macintosh HD step by step:
1.Start Disk Utility
2.Source volume select from the list
3.Right to the tab "Restore Activate
4.source and destination drag and drop to the fields
5.For a 1:1 copy "delete destination media"
6.Click on "Restore" button and confirm
7.copy will start ...
Before the backup process, it is recommended to remove the rights of the source volume and thereby ensure that the destination disk is smaller than the source.