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File Backup

If you are backing up to a hard drive with the Update backup type, then the data of the
previous backup will be overwritten with the changed data. This means that older ver-
sions will be erased; access to older backup states will no longer be possible.

If you are backing up to the disc on which the last backup was burned with the Update
backup type, then the procedure is the same as described for the Incremental backup.
In this case a folder will be generated in a new session.
With the three Full, Incremental and Differential backup types, it does not matter which
medium you save the backup to. You can, for example, use the disc that you used for the old
backup (Nero BackItUp automatically started a multisession disc) as long as there is still
space on the disc. You can also back up to a new medium.
Incremental Backup (Above) and Differential Backup (Below)
An example is provided below to illustrate the difference between incremental and differential
backups:
Let's assume that you have 100 photos and are backing them up. The first (full) backup con-
tains the 100 photos. Then you change 25 of the photos and want to back up again. You se-
lect an incremental or differential backup (it does not matter which you select for the second
backup). The 25 changed photos are backed up. Then you change another 10 photos and
want to back up again:
If you select the Incremental backup, 10 photos are backed up, specifically those that have
changed since the last backup. (Nero BackItUp compares the current status with the last
backup.)
If you select the Differential backup, 35 photos are backed up, specifically those that have
changed since the first backup. (Nero BackItUp compares the current status with the first
backup.)
This means that incremental backups require less storage space, however usually more
backup versions will have been created. The result is that the restore takes longer since ma-
ny small versions must be restored (and made ready) one after the other.
The opposite is true of the differential backup: It requires more storage space, however only
two backup versions (the first and the last) are needed. Consequently, for the restore only
two versions are restored (and made ready) because the last version contains all changes
made since the first backup.
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