Incremental backup
Also known as: incremental backup vs differential, changed-files backup
An incremental backup saves only what changed since the previous backup — full or incremental. Each run is small and fast, but restoring requires the full backup plus every incremental in the chain, in order.
- Saves only changes since the previous backup
- Small and fast to run; uses the least space
- Restore needs the full backup plus the whole chain
How incremental backups work
After an initial full backup, each incremental backup copies only the data that changed since the last backup of any kind. Because it captures just the latest changes, each incremental is small and quick to create, which keeps daily backup windows short and storage use low.
The cost shows up at restore time. Rebuilding the data means starting from the full backup and applying every incremental in sequence, so the more incrementals you have accumulated, the longer and more failure-prone the restore.
Choosing incremental, differential, or full
Incremental is the most storage- and time-efficient for routine backups; differential trades extra space for simpler restores; a periodic full backup resets the chain so restores never depend on too many steps. Many backup tools combine them — for example, weekly fulls with daily incrementals.
A reliable plan also keeps multiple recovery points and stores at least one copy off the device, so a single failed file in the chain or a lost machine does not take down your only backup.