The 3-2-1 rule is the guiding principle of data backup and disaster recovery. The rule states that in order to have a reliable, redundant backup and an effective disaster recovery solution, you must have: three copies of your data, on two forms of media, with one copy located offsite.
The rule itself is simple enough to understand, but it can be a bit difficult to execute. When and where to begin the implementation of the 3-2-1 rule is largely dependent upon your current backup and DR solutions. Let’s break this down.
Three: Obtain at least 3 copies of data
How are you currently backing up your data? Or do you not currently have a backup strategy at all? The 3-2-1 rule states that at all times there must be three copies of data. This means that, in addition to the original copy of data, you should be replicating that data to two additional backup files. Establishing redundancy in your backup strategy is important in reducing the risk of lost data due to degradation, loss, and potential disasters.
To give an example:
Imagine having two devices, one for the original data, and one for the backup. Let’s say these two devices are statistically independent to each other, and their probability of failure is 1/100. For one device, this alone holds too much of a risk. This can be avoided with the implementation of two devices. The chances of both failing at the same time would be 1/10,000 (1/100 * 1/100). Now picture this three times instead of two. The chances of all three failing at the same time is now 1/1,000,000. Thus having 3 copies of data is all about reducing the probability of risk to your business.
Two: data copies need to be stored on two different media
If you have an established backup strategy, what media are you currently using to back up your data? Generally, companies utilize tape, disk and/or cloud for data backups. As previously explained, data backups should be stored on two different forms of media to ensure business continuity in the event that one media fails. It’s like having a lifeboat for a cruise ship: you hope you never need it, but if your ship sinks you thank your lucky stars you have a backup! In other words, don’t create the Titanic of data backup, always be prepared with a second type of media.
One: Keep one backup copy offsite
Do you currently use an offsite repository or environment for your backups? If not, your company is at risk for data loss. Consider the consequences of your office being hit by a disaster. The entire system is out onsite, including the onsite failover for your data. How is your business affected? Preventing catastrophic loss goes beyond the loss of data to include the loss of revenue, the loss of people and the loss of your entire business. Having an offsite repository helps to ensure that when a disaster strikes at home, you can still operate business as usual. You can sleep easy knowing that in the case of a fire, flood, or any other form of disaster your data is safe.
Now that you know the 3-2-1 rule you can start identifying the areas of concern within your own business. At the end of the day business continuity and disaster recovery plans need a strong backup strategy to be successful. Which means, contrary to popular belief, that your business needs to implement BOTH Backup and Disaster Recovery solutions to ensure the proper restoration of data in an emergency. The 3-2-1 rule gives you the backbone, but creating an overall DR plan forms the meat and potatoes of your business continuity solution. In other words, start building your lifeboat today, don’t wait for your ship to sink!