Differential backup and incremental backup are two common data backup strategies, both designed to optimize storage and recovery processes, but they differ significantly in how they handle and store backup data.
Differential Backup
A differential backup captures all the changes made since the last full backup. Unlike an incremental backup, it does not rely on the previous differential or incremental backups for restoration.
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How it works:
- A full backup is taken first (e.g., on Sunday).
- The next differential backup (e.g., on Monday) includes all changes since the last full backup (Sunday).
- The following differential backup (e.g., on Tuesday) again includes all changes since the last full backup (Sunday), not just Monday’s changes.
- This means each differential backup grows larger over time as it accumulates more changes.
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Restoration process:
- To restore data, only the last full backup and the latest differential backup are needed.
- Example: If you have a full backup from Sunday and a differential from Wednesday, you only need those two to recover all data up to Wednesday.
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Example:
- Full Backup (Sunday): Files A, B, C.
- Differential (Monday): Changes to File B → Backup includes A, B (updated), C.
- Differential (Tuesday): Changes to File C → Backup includes A, B (updated), C (updated).
- Restoration (Wednesday): Restore Sunday’s full backup + Tuesday’s differential.
Incremental Backup
An incremental backup only stores the changes made since the last backup (full or incremental). Each backup is smaller, but recovery requires multiple steps.
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How it works:
- A full backup is taken first (e.g., on Sunday).
- The next incremental backup (e.g., on Monday) includes only changes since Sunday’s full backup.
- The following incremental backup (e.g., on Tuesday) includes only changes since Monday’s incremental backup.
- Each subsequent backup is smaller but depends on all previous backups for recovery.
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Restoration process:
- To restore data, you need the last full backup and all incremental backups up to the desired point.
- Example: If you have a full backup from Sunday and incrementals from Monday and Tuesday, you must restore all three to get data up to Tuesday.
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Example:
- Full Backup (Sunday): Files A, B, C.
- Incremental (Monday): Changes to File B → Backup includes only B (updated).
- Incremental (Tuesday): Changes to File C → Backup includes only C (updated).
- Restoration (Wednesday): Restore Sunday’s full backup + Monday’s incremental + Tuesday’s incremental.
Key Differences
| Feature |
Differential Backup |
Incremental Backup |
| Backup Scope |
Changes since last full backup |
Changes since last backup (any type) |
| Backup Size |
Grows larger over time |
Smaller, but depends on frequency |
| Restoration Speed |
Faster (only full + latest differential) |
Slower (requires full + all incrementals) |
| Storage Efficiency |
Less efficient (backups grow) |
More efficient (smaller backups) |
When to Use Which?
- Differential Backup is better when you want faster recovery with fewer files to restore. It is suitable for environments where quick restoration is critical.
- Incremental Backup is better when storage space is limited, and you can afford a longer recovery time.
In cloud environments, services like Tencent Cloud’s CBS (Cloud Block Storage) snapshots or Tencent Cloud Object Storage (COS) versioning can be used to implement these backup strategies efficiently. For automated backup management, Tencent Cloud Backup solutions provide flexible scheduling and recovery options.