Questions
- What is the difference between a full backup, incremental backup, and differential backup?
- Why is the 3-2-1 rule recommended for backups, and what does it mean in practice?
- How often should I back up my personal files (photos, documents, etc.)?
- What are common types of storage media for backups, and what are their pros/cons?
- How can I verify that my backups are usable and not corrupted?
- What steps should I take to protect backups from ransomware and other threats?
Answers
- Full backup: Copies all selected data every time. Fast restores but requires the most storage and time to create.
- Incremental backup: After the initial full backup, only changes since the last backup are saved. Fast initial backups and low storage, but restores require the chain of backups (most recent full + all incrementals).
- Differential backup: After the initial full backup, saves all changes since the last full backup. Slower than incremental over time, but restores only require the last full backup plus the latest differential.
- 3-2-1 rule: Have three copies of your data, on two different media, with one copy offsite.
- Practical: Original data + 2 backups (e.g., local external drive and cloud storage), and keep at least one backup disconnected or in a separate location (offsite) like cloud or a physically separate device in another location.
- Frequency depends on how often data changes and its importance. For critical data (photos, documents, work files): daily or near-daily backups; for less critical data, weekly with continuous or continuous-incremental backups for ongoing work. Implement auto-backups where possible and at least weekly bulk backups.
- External hard drives: Cheap and fast for local backups; risk of hardware failure and theft; rotate if possible.
- Network Attached Storage (NAS): Centralized backups for multiple devices; supports RAID but not a substitute for offsite backups.
- Cloud backups: Offsite, protected from local disasters; ongoing costs; dependent on internet; consider encryption and privacy policies.
- USB flash drives: Portable but low capacity and reliability for large datasets.
- Tape (long-term archival): cheap per TB for cold storage; slower access but durable; uncommon for home users.
- Pros/Cons summary: Local media (fast restores, high reliability if redundant) vs. Offsite/cloud (protection against local disasters, potential ongoing costs, internet dependency). A mix is ideal.
- Regular integrity checks: Run verification after backups (compare file checksums, run test restores).
- Random restores: Periodically restore a subset of files to ensure data is usable.
- Use checksums or hash verification for large datasets to detect corruption.
- Keep backups organized and labeled so you know what’s in each set and when it was created.
- Encrypt backups if they contain sensitive data and ensure proper key management.
- Ransomware-resilient backups: Keep offline or air-gapped backups (not continuously networked) to prevent encryption by ransomware.
- Versioning: Use backups that retain multiple restore points to recover from a ransomware event before encryption occurred.
- Access controls: Limit who can modify or delete backups; use MFA; segment backup storage.
- Regular testing: Verify restores and integrity; ensure you can restore clean copies.
- Encryption at rest and in transit: Protect backup data from theft or interception.
- Infected device isolation: If a device is compromised, isolate it from the backup network to prevent spread.