A NAS on the shelf is not a backup

In many small offices the backup is a small black box on a shelf, blinking beside the router. It holds the shared files, the scans, the old projects and, often, the nightly backups of everything else. Everyone knows it is there. Few people know what it would survive.

A NAS (network-attached storage, a box of disks shared over the office network) is a good piece of equipment. It is not, on its own, a backup. Here is why, and what it takes to make it part of one.

What a NAS does well

A NAS earns its place:

• Fast local restores: pulling a folder back over the office network is quicker than from anywhere else.
• Cheap capacity: a few large disks hold years of files at a low cost per terabyte.
• A shared home: one place for scans, project files and archives, instead of a dozen laptops.
• A landing spot: PCs and servers can back up to it overnight.

Keep all of that. The problem is not the box. The problem is treating one box as the whole plan.

RAID keeps the box running

Most NAS units use RAID, which spreads data across several disks so the box keeps working when one disk fails. Owners often take this as a backup. It is not one.

RAID protects against a single kind of failure: a dead disk. Everything else is copied instantly to every disk in the set. Delete a folder and it is deleted on all disks at once. Let ransomware encrypt a share and every disk holds the encrypted version. RAID is about staying up. A backup is about having an earlier, separate copy.

Five ways one box fails

1. The room. Fire, water from a burst pipe or roof leak, a power surge or a break-in all reach the NAS and the computers beside it at the same moment.
2. Ransomware. If PCs map the NAS as a drive letter, malware running on one PC can usually write to it. CISA’s #StopRansomware Guide warns that “many ransomware variants attempt to find and subsequently delete or encrypt accessible backups to make restoration impossible unless the ransom is paid.” A NAS on the same network, signed in with office accounts, is an accessible backup.
3. The admin password. Whoever holds the NAS admin account can delete its snapshots and backup sets. If that password is shared, reused or stolen, so is the backup.
4. Quiet failure. Backup jobs to a NAS stop when a disk fills up, a password changes or a PC is replaced. The alert goes to an inbox nobody reads, and the newest copy is months old on the day it is needed.
5. Age. Controllers fail, models go out of support, and disks bought on the same day wear out on a similar schedule.

None of these is unusual in a small office. Each one is fixed by the same idea: a second copy somewhere the first one’s problems cannot reach.

When the NAS is the original

There is a common arrangement that looks like two copies and is really one. The shared files live on the NAS, and the backups of the PCs also live on the NAS. For the shared files, the NAS is the original. Nothing else holds them.

Ask a plain question about every folder on it: if this box disappeared tonight, where else would this folder exist? If the answer is nowhere, that folder has no backup.

What turns it into a backup

You do not need to replace the NAS. You need to put it in its place as the fast local copy, then add what it lacks.

• A second copy off site. In a different region, not across town. Off site should mean far away explains why distance matters.
• A copy nobody in the office can change. An immutable copy is locked for a set period, so even an admin account cannot delete or alter it. The Immutable Offsite Copy plan keeps a locked copy of a NAS in a second US region at least 500 miles away, locked for 30 days by default and up to 1 year, from $15 per TB per month.
• Separate credentials. The account that writes to the off-site copy should not be one anyone signs in with every day, and the NAS admin account should have two-factor sign-in.
• Read-only snapshots. Turn them on. They help with deletions, but they live in the same box, so they are not the off-site copy.
• A person reading the alerts. With automated system backup, every job is watched and a failed one is followed up the same business day.
• A restore test. Pull a real folder back from the off-site copy at least once a quarter.

If the NAS is also your file server, its shares can sit inside the Server Backup plan instead, which covers NAS shares alongside servers. The 3-2-1 backup rule is the short version of all of this.

Which copy to restore from

Once the NAS has a far copy behind it, each one has a clear job. It helps to agree those jobs in advance, so nobody has to decide on a bad day.

• A deleted file or folder: restore from the NAS snapshot. It is the fastest route, often minutes.
• A failed disk: let RAID carry on, replace the disk, and check the rebuild finished.
• A failed NAS: restore the most-used shares from the far copy to a replacement box or a server, newest work first.
• Ransomware, fire, water or theft: treat the NAS as lost. Restore from the locked far copy, once the cause is contained.

Write those four lines into your recovery steps. They turn “what do we do?” into “which line are we on?”

Example: ransomware reaches an agency’s NAS

Take an 18-person marketing agency. Its NAS holds 4 TB of client artwork, contracts and invoices. Every PC maps it as drive S:. Each night the NAS copies itself to a USB drive plugged into its back port, and the owner thinks of that drive as the backup.

On a Monday at 10 a.m., someone opens a malicious attachment. By noon the files on S: are encrypted. So is the USB drive, because it was mounted on the NAS and reachable through it. Both copies are gone at once, which is exactly the pattern CISA describes.

Now run the same Monday with a locked copy in a second region. The last locked copy, taken on Sunday night, is sealed for 30 days, and no account in the agency can change it. Once the PCs are cleaned and the NAS is wiped, with the insurer and counsel informed, the restore begins. Restoring 4 TB over an office internet line takes time, so the order matters: the folders for this week’s client work come back first, then the archive over the following days.

The locked copy costs 4 TB at $15, or $60 a month. The question for the owner is not whether to keep the NAS. It is whether one more copy, out of reach, is worth $60 a month.

A NAS checklist for this week

Go through these with whoever looks after the box:

• Is any folder stored only on the NAS?
• Which PCs map a NAS share, and do they all need to write to it?
• Is there a copy outside the building that office accounts cannot delete?
• Does the NAS admin account have its own password and two-factor sign-in?
• Are read-only snapshots switched on, and how many days do they keep?
• Who receives the NAS alerts, and when did someone last read one?
• When was a folder last restored from the off-site copy?
• How old are the NAS and its disks?

The 3-2-1 backup checklist turns these into 12 points you can tick off on one page.

A calm next step

If your NAS holds anything you would miss, it is worth a few minutes to find out what else holds it too. The free backup check is 45 minutes, remote, with one test restore and a written page of findings. Book a free backup check and bring along whoever manages the NAS.