What is the 3-2-1 Backup Rule and Why Do Your or Your Business Need it?
In a world of constantly changing technologies and their demand for bigger, better and faster ways of storing data, best practices for data governance can quickly evolve. This has not been the case for the 3-2-1 backup rule. This golden rule has withstood the test of time and applies to everything, from data stored on physical hardware or virtual machines, either locally or on a provider’s infrastructure.
Everyone should have a backup. This principle works for any environment; regardless of the technology that you are using: backup is king!One of the timeless rules that can effectively address any failure scenario is called the 3-2-1 backup rule. This approach helps to answer two important questions: how many backup files should I have and where should I store them?
The 3-2-1 rule became a popular concept thanks to Peter Krogh, a well-known photographer who wrote that there are two groups of people: those who have already had a storage failure and those who will have one in the future. In other words, the 3-2-1 backup rule means you should:
- Have at least three copies of your data.
- Store the copies on two different media.
- Keep one backup copy offsite.
Let’s consider these statements one by one in more details.
1. Have at least three copies of dataBy three copies, I mean that in addition to your primary data, you should also have at least two more backups. Why isn’t one backup enough? Imagine that you keep your original data on device #1 and its backup is on device #2. Both devices have the same characteristics, and their failures are statistically independent (they have no common failure causes). For example, if device #1 has a probability of failure that’s 1/100 (and the same is true for device #2), then the probability of failure of both devices at the same time is:
1/100 * 1/100 = 1/10,000
This means that if you have your primary data (on device #1) and two backups of it (on devices #2 and #3, correspondingly), and if all devices have the same characteristics and no common failure causes, then the probability of failure of all three devices at the same time will be:
1/100 * 1/100 * 1/100 = 1/1,000,000
This is why having more copies of your data means you will have less risk of losing data during a disaster. In short, if your data is important to you, be sure to make at least two backup copies.
Note: Another reason to create more than two copies of data is to avoid the situation when the primary copy and its backup are stored in the same physical location.
2. Store the copies on two different mediaIn the section above, we assumed that there were no common failure causes for all of the devices where you store your data copies. Obviously, this requirement cannot be fulfilled if you save your primary data and its backup in the same place. (For example, disks from the same RAID aren’t statistically independent.) Moreover, it is not uncommon after one disk failure, to experience failure of another disk from the same storage around the same time.
That’s why the 3-2-1 rule suggests that you keep copies of your data on at least two different storage types, such as internal hard disk drives AND removable storage media (tapes, external hard drives, USB drives, SD-cards, CDs, DVDs, or even floppy disks), or on two internal hard disk drives in different storage locations.
3. Keep one backup copy offsitePhysical separation between copies is important. It’s really not a good idea to keep your external storage device in the same room as your production storage. If there was a fire (knock on wood!), you would lose all of your data.
If you work for a company that’s an SMB with no remote or branch offices (ROBO), storing your backups to the cloud might also be an option. And tapes taken offsite are still popular among all company sizes.
iON understood the need for a solution that fits with the reality SMBs face and chose to partner with Veeam, the internationally-known VM backup solution provider. By using iON Performance Cloud servers and Veeam’s Cloud Connect backup solution, our partners and their clients can build an effective Disaster Recovery plan. This is an enterprise-grade solution with an SMB price tag.