A solid rule of thumb for good backups is the **3-2-1 backup strategy**:
1. **3 Copies of Data**: Keep at least three copies of your data—one primary copy and two backups. This redundancy protects against data loss from various types of failures.
2. **2 Different Storage Types**: Store the copies on at least two different media types, such as an external hard drive, network-attached storage (NAS), or cloud storage. Using varied storage types helps protect against failures specific to a single storage method.
3. **1 Offsite Copy**: Keep one backup copy offsite to guard against data loss from physical disasters, like fires or floods, that could affect all onsite copies.
Additionally, here are a few extra best practices:
- **Automate Backups**: To ensure regular backups, automate the process where possible.
- **Verify Backups**: Test backups periodically to confirm the data is recoverable.
- **Follow a Retention Policy**: Decide how long you need to retain backup copies, balancing storage costs with recovery needs.
- **Use Encryption**: Encrypt sensitive data backups, especially if they are stored offsite or in the cloud.
This approach provides a resilient system that can recover data quickly in case of accidental deletion, hardware failure, or catastrophic events.