Differential Backup

With the mode "Differntial Backup" it is possible to save only new files and files that have changed since the last complete backup. A full backup is always used as a reference to determine which files should be saved. The list of all files to be saved and the date of the last backup is extracted from this full backup. Only entries in the file list which have a newer date will be saved.
An existing backup job (which is used as a reference) must be selected in order to do a differential backup. For this reason the file selection is replaced by the list of existing backup jobs. This is exactly the same list that is shown in the JobQueue window of SIEGFRIED BACKUP. The only difference is, that all none backup jobs are filtered. Only a single backup job can be selected as a reference for a differential backup.
SIEGFRIED BACKUP automatically uses the title of the selected full backup job as the new title for the differential backup.
A differential backup always deactivates the overwrite mode of the destination drive!

For example:
A full backup should be created every Sunday. Only those files should be saved that have been modified since Sunday on every other day of the week.
Two jobs must be created to do such a backup. The first job is a full backup. All drives/directories/files to backup must be marked. "Overwrite" should be selected at the destination setting to save backup space.
The repeat interval of the full backup is set to 1 day. Monday through Friday should be excluded in the selection which then confines the full backup to Sundays.
A unique title should be set (i.e. "Backup of all my pictures") in the backup start window.
After the job is started the second job, the differential backup, can be created. Select the backup mode "Differential". The backup window now shows all backup jobs instead of the file list. Select the job with the title "Backup of all my pictures" as a reference for the differential backup.
The destination of the differential backup should be the same as in the full backup. This isn't absolutely necessary, but it's a good idea to to simplify keeping track of backups that belong to each another.
The one day repeat interval is used in the scheduler. Sunday should be excluded. This ensures that the differential backup runs on every day except Sunday.
The backup start window automatically uses the title of the full backup.
The backup proceeds as follows after the job start:
The first full backup starts on Sunday. It saves all selected files. On monday the differential backup is started. The file list and date of the last backup are extracted from the job data of the full backup. By using this date all entries of the file list are removed which are older (not modified). The cleaned file list is used for the backup. The saved data is placed in the same destination as the full backup (the data of the full backup will not be overwritten).
The differential backup will be repeated every day until next Sunday. Only entries that have been modified since Sunday will be saved.
On next Sunday the full backup starts again. If "overwrite" is activated, all backup data of the full and differential backup jobs will be deleted because they are placed at the same destination. After that a new complete backup is created.

A differential backup needs more space on the destination drive than an incremental backup. But the restoration of a differential backup is easier than an incremental backup, because only the full backup and the last differential backup must be restored for a complete restoration. For an incremental backup the full backup must be restored followed by all incremental backups in the correct order of their creation.