Backups: the 3-2-1 rule and why you should test them
Most companies have backups, but few have ever tried to restore data from them. A simple rule and five checks worth doing this month.
A backup you have never tried to restore is not a backup but an assumption. Companies usually discover this at the worst moment: after a disk failure, an accidental deletion or an attack that locked the data.
The 3-2-1 rule
The rule is old and simple, and it still holds:
- Three copies of the data: the original and two backups.
- Two different media or systems, so one failure does not destroy both.
- One copy at another location, outside the office.
Today a fourth condition is often added: at least one copy must be such that an attacker cannot alter or delete it, even after taking over your network.
The most common mistakes
- The backup is on a disk permanently connected to the same computer or network, so it is lost together with the original.
- Documents are backed up, but not the database, email or system settings.
- Backups have been failing for months and nobody reads the notifications.
- One person knows the backup password.
- Nobody knows how long a restore would take.
Five checks for this month
- List what is backed up. Compare it with the list of what you cannot work without.
- Check the date of the last successful backup. For each system separately.
- Restore one file and one whole folder. To another computer, not over the original.
- Measure the time. How long would it take to restore everything, and can the business stand still for that long?
- Write down the procedure. Who restores the data, from where and in what order.
How often
The question is not how often you want to back up but how much work you can afford to lose. If the answer is one day, the backup must be daily. If it is one hour, you need a different solution. That decision belongs to management, not the technician.
Regular backup checks are part of the IT maintenance we provide to business users.
