A method and system of data backup for a computer system is disclosed. Full and incremental backups of data stored to a first storage device coupled to the computer system are stored to a backup storage device coupled to the computer system. The backup storage device may be remotely located and coupled via a network. Data representative of the relationship of each incremental backup to its respective parent backup is stored in a dependency data structure, preferably a tree-like structure. Different types of incremental backups may be performed to provide different data granularity. When two or more storage media are used in a rotational manner, each medium always contains a complete backup. The backup storage device is automatically managed by paring at least one of a full and incremental backup at the backup storage device automatically in accordance with a plan. The plan is preferably configured to manage an amount of available storage space at the backup storage device. When restoring data from a backup, data to be restored that is stored in a parent backup is automatically located and restored. Stored backups may be encrypted and decrypted when restored.