A Backup You Have Never Tested Is Not a Backup

Ask a business owner whether their data is backed up and most will say yes. Ask when someone last opened a backup and checked it, and the room goes quiet.

Before the mill's ERP existed, years of production records lived in one file on one computer. A single failed disk would have taken all of it. When I built the new system, the backup was not an extra. It was part of the design.

What usually goes wrong

• The backup depends on a person. It works until that person is busy, ill or on leave.
• The copy is on the same computer. A dead disk, a fire or a theft takes the data and its backup together.
• Nobody checks the file. A backup cut short by a dropped connection still has a normal-looking name and size.
• Copies pile up for ever, the disk fills, and new backups quietly stop.

I have seen a backup job fail every night for days because one small tool was missing on the server. Nothing looked wrong. No error appeared on any screen. That is what makes backup failures dangerous: you find out on the day you need the backup.

The nightly backup I run

Every night, with no person involved, a script does five things.

1. Take a consistent copy without stopping work

The database is copied as one consistent snapshot. Nobody is locked out, and the copy does not contain half-saved entries.

2. Compress it

The copy is compressed so it is small enough to move and keep.

3. Verify it

This is the step most setups skip. The script checks that the file is complete and can be read. A broken backup is found tonight, not in six months.

4. Send it off-site

The verified file is uploaded to cloud storage away from the factory. If the server room is lost, the data is not.

5. Remove old copies

Copies older than 30 days are deleted automatically, so the storage never fills up.

Two details that matter more than they look

The backup is started by the operating system, not by the application. If the ERP itself is down, the backup still runs. A backup that only works when everything else is working is not much of a backup.

The system shows the backup status. An administrator can see when the last good backup ran. Silence is not treated as success.

The 3-2-1 rule, in plain words

• Keep 3 copies of your data
• On 2 different kinds of storage
• With 1 copy somewhere else

It is an old rule and it still works.

Test the restore

Once in a while, take last night's backup and restore it on another machine. Open a report you know well and compare the numbers. Until you have done this, you have a file, not a backup.

A five-minute check for your business

1. Where is your backup right now?
2. Does it run without anyone remembering?
3. Is a copy kept outside the building?
4. Has anyone ever restored from it?
5. Who is told when it fails?

If you could not answer all five, your business is carrying a risk that is cheap to remove. The full setup is described in the reporting, backup and audit project. If you want this for your own database, tell me what you run today.