Term: incremental backup

An incremental backup is a backup of only those files which have changed since an immediately preceding backup. The term derives from the word “increment”, in that only an increment of the entire collection of files may be included in the backup.

Incremental backups are used as space-saving alternatives to full image backups, which backup everything.

An incremental backup is used when a series of backups is being taken periodically. The first backup taken is a full backup of everything, but each subsequent backup in the series is incremental, backing up only those files which have been modified since preceding backup.

While incremental backups do save space, they have an explicit built-in dependency – in order to recover an entire collection of files to its most recent state, the initial full backup, plus all the intervening incremental backups, must be used.

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