Which of the following backup strategies is generally considered the most efficient in terms of storage usage?

• A. Full backup
• B. Differential backup
• C. Incremental backup
• D. Copy backup

Answer: (C)

Incremental backup is recognized for its efficiency in terms of storage usage because it only backs up the data that has changed since the last backup was performed, whether that was a full backup or another incremental backup. This means that each incremental backup file is smaller in size compared to full and differential backups, which capture more data.

In a full backup, all data is copied regardless of any previous backups, leading to significantly larger file sizes and longer backup times. Differential backups, while more efficient than full backups, back up all changes made since the last full backup; therefore, they can still grow large over time as more changes accrue.

The copy backup is used primarily to create a duplicate of data in its existing state and does not consider prior backups. This strategy can also result in higher storage usage since it does not implement the incremental model of only capturing changes.

Thus, to minimize storage requirements whilst maintaining effective backup operations, an incremental backup strategy is the most efficient.