Understand Differential Backup Vs Incremental Backup: What's the Difference?
Published: 2024-02-12 11:32:31

In the realm of data protection and backup strategies, two terms that often come up are "differential backup" and "incremental backup." While both serve the purpose of safeguarding data, they employ distinct methodologies and have their unique advantages and disadvantages. Let's delve into each method to understand how they work and when to use them:

**Differential Backup:**

Differential backup involves copying all the data that has changed since the last full backup. Here's how it works:

1. **Initial Full Backup**: In a typical backup routine, the first step is to perform a full backup. This backup captures all the data in its entirety and serves as the baseline for subsequent backups.

2. **Subsequent Differential Backups**: After the initial full backup, each subsequent backup captures all the data that has changed or been added since the last full backup. Unlike incremental backups, which only capture changes since the last backup of any kind, differentials always capture changes since the last full backup.

3. **Storage Requirement**: While differential backups are relatively faster to perform than full backups and provide quicker restore times compared to incremental backups, they require more storage space over time. This is because each differential backup includes all changes since the last full backup.

**Incremental Backup:**

Incremental backup, on the other hand, captures only the data that has changed since the last backup, regardless of whether it was a full, incremental, or differential backup. Here's how it works:

1. **Initial Full Backup**: Similar to differential backups, incremental backups start with a full backup of all data.

2. **Subsequent Incremental Backups**: After the initial full backup, each incremental backup captures only the data that has changed since the last backup of any kind, whether it was a full, incremental, or differential backup.

3. **Storage Efficiency**: Incremental backups are more storage-efficient compared to differential backups because they only store changed data since the last backup, minimizing the amount of storage space required over time.

**Comparison:**

- **Restore Process**: Restoring from a differential backup typically requires only the latest full backup and the most recent differential backup, making the restore process relatively straightforward. In contrast, restoring from incremental backups may involve retrieving multiple backup sets, including the initial full backup and all subsequent incremental backups since then.

- **Storage Efficiency**: Incremental backups are more storage-efficient since they only store changes since the last backup, while differential backups grow in size over time as they include all changes since the last full backup.

- **Backup Duration**: Incremental backups generally take less time to complete compared to differential backups since they only need to capture changed data since the last backup, reducing the backup window.

In summary, the choice between differential and incremental backups depends on factors such as storage capacity, backup window, and restore requirements. While differential backups offer simplicity in the restore process, incremental backups provide better storage efficiency. Organizations often use a combination of these backup strategies based on their specific needs and data management policies.