Incremental Backup
What is incremental backup?
Incremental backup is a data backup method that copies and stores only the files or data blocks that have changed since the last backup operation. Instead of backing up the entire dataset each time, this approach focuses only on new or modified data, making the backup process faster and more efficient.
This method is widely used in cloud backup systems, enterprise IT environments, and disaster recovery solutions because it significantly reduces storage space requirements, network bandwidth usage, and backup time.
How does incremental backup work?
If an organization chooses to implement an incremental backup, it is typically carried out through the following steps:
1. An initial full backup:
The first step is to run an initial full backup to completely backup all the necessary files in one single time. A full backup involves completely copying all the organization's files in one single backup operation.
For example, the organisation may schedule a full backup every Sunday.
2. Only changed data is captured:
After the first full backup, incremental backups are scheduled periodically. Each incremental backup saves only the data that has changed since the last backup, whether that the backup was a full or incremental one.
For example, after the full backup on Sunday, incremental backups run every day until Saturday.
- On Monday, the incremental backup copies only the files that have changed since the complete backup performed on Sunday.
- On Tuesday, it copies only files modified after Monday's incremental backup. This continues each day until the next full backup is done.
3. Restoration:
In the event of a system crash, to recover the data fully, you must restore the initial full backup along with all subsequent incremental backups, in the correct sequence.
For example, if a crash occurs on Friday, you would need to restore:
- Sunday's full backup
- Monday's incremental backup
- Tuesday's incremental backup
- Wednesday's incremental backup
- Thursday's incremental backup
- Friday's incremental backup (if completed before the crash)
Full backup vs incremental backup vs differential backup
Full backup: Each time the backup process runs, it creates a complete duplicate of all your chosen data.
Incremental backup: Saves only the changes made since the last backup (whether it was full or incremental).
Differential backup: Captures all changes made since the last full backup.
Advantages of incremental backup
1. Reduced storage usage:
Only changed data is backed up after the first full backup, which significantly reduces the amount of storage required.
2. Faster backup process:
Since only modified files are copied, backup operations complete much faster compared to full backups.
3. Lower network bandwidth consumption:
Transferring smaller data volumes reduces network load, making it ideal for cloud and remote backups.
4. More frequent backups possible:
Because backups are faster and lighter, organizations can schedule them more frequently, improving data protection.
5. Cost efficiency:
Less storage and bandwidth usage result in lower infrastructure and cloud service costs.
6. Improved backup automation:
Well-suited for automated backup systems that run at regular short intervals without affecting users.
Limitations of incremental backup
- The restoration process is more complex and slower because it requires the initial full backup and all subsequent incremental backups in the correct sequence.
- Backup verification is more complex because the entire backup chain must be validated, not just individual files.
- There is a higher risk of data loss if any single backup in the chain is missing or corrupted.
- There is increased management overhead to maintain the backup chain, which can make it harder to meet fast recovery time objectives (RTO).
Common use cases for incremental backup
- Configurations requiring consistent or frequent backup routines.
- Large data sets.
- Settings characterized by restricted storage or bandwidth, like remote work configurations or cloud-based systems.