How to Back Up a NAS Against Drive Failure and Ransomware

Back up the NAS to a second location it cannot reach with its own credentials, keep at least one immutable or offline copy, layer local snapshots for fast rollback, and test a restore quarterly. RAID and snapshots handle hardware and mistakes. An isolated offsite copy is the layer that handles ransomware.

Why is RAID not a backup?

RAID protects against a disk failing. Accidental deletion, firmware corruption, a failed controller, theft, fire, and an attacker with admin credentials all hit the whole array at once, and parity does nothing about any of them.

Treat RAID as uptime insurance and backup as recovery insurance. A five-bay array can lose a disk on Monday and lose every file on Tuesday, and both days look normal in the dashboard.

How should you structure NAS data protection?

Build it in four layers, from fastest recovery to strongest isolation.

Layer 1: Local snapshots

Enable scheduled snapshots on the NAS with a retention schedule such as hourly for a day, daily for a month. Snapshots restore an accidental deletion in seconds. Store them read-only.

Never rely on this layer alone. An attacker with NAS admin access can usually delete every snapshot you have, and deleting them is step one of the playbook.

Layer 2: A second copy on separate hardware

Replicate to another NAS or a server on different storage, ideally in a different physical location. This covers device failure, theft, and site problems.

Layer 3: An immutable offsite cloud copy

Send backups to cloud storage with object lock or equivalent immutability, using credentials that exist only in the backup service and never on the appliance. This is the layer that survives ransomware. If the NAS can delete it, it is not this layer.

Layer 4: A periodic offline copy

For your most critical data, keep a copy that is physically disconnected, rotated on a defined schedule. It is inconvenient by design, which is exactly why it works. 

Those four layers are the 3-2-1-1-0 rule applied to the storage attackers reach first. Immutable is a copy. Recovery is a company.

How do you harden NAS security itself?

• Disable direct internet exposure and remove any port forwarding to the NAS admin interface.
• Require multi-factor authentication for every administrative account.
• Replace default admin accounts and remove unused shares and services.
• Keep firmware current, since NAS vulnerabilities get scanned for within days of disclosure.
• Use separate credentials for backup jobs, scoped to write-only where the platform allows it.
• Turn off SMBv1 and restrict share permissions to the minimum each role needs.
• Now assume all of that failed and somebody has the admin password tonight. What still exists tomorrow morning is your actual ransomware recovery position.

How do you know it works?

Restore something on a schedule. Recover a single file monthly and a full share quarterly, from the offsite copy, and record how long it took.

Snapshot restores prove nothing about your ransomware position, because that scenario assumes the NAS itself is already compromised. Work through these disaster recovery test questions and put a real number next to each one.

Frequently asked questions

Can a NAS back itself up to the cloud? Most can, using built-in sync or backup apps. The catch is that credentials stored on the NAS can often be used to delete the cloud copies, which means the appliance you are protecting holds the keys to its own backups.

Are NAS snapshots enough against ransomware? No. Snapshots are excellent for accidental deletion and fast rollback, and an attacker with admin access can typically remove them. Immutable offsite copies are the safeguard.

Next step

CyberFortress holds the immutable copy your NAS credentials cannot touch, monitors every job, and times the restore so the number belongs to you.

Prove Your Recovery · Test Your Fortress

Related reading: Protecting backups from ransomware