3-2-1 backup strategy, what is it?

A close up images of a SATA hard drive.
(Image credit: Pixabay)

Every user, business and organization that uses a computing device generates data, which needs to be stored. While storing data is not generally considered much of a challenge these days, as computers have a solid state or hard drive to write the data to, and the data, when requested, can then be read off of.

However, with the data written on only a single drive, the adage of “There are two categories of computer users, those that have lost data, and those that will lose data” definitely applies. Therefore, the goal should always be to have multiple copies of the data, so that if (or maybe more accurately when) one drive fails, that there is another copy of the data elsewhere, which is the ‘Plan B.’ In fact, experts recommend that this gets taken even a step further, and that you have a ‘Plan C,’ which is to have a third copy of the data, so that there is a high likelihood that whatever happens at least one copy of the data is retained.

As easy a 3,2,1

There are many options to store data, and this is where the confusion happens. After all, nobody wants to lose data to figure out that their strategy is not ideal. In fact, with options these days from hard drives, solid state drives, flash drives, removable storage media, and cloud storage. There is also the issue of direct attached storage versus network storage, and onsite versus offsite storage solutions. It can easily progress somewhere from confusing to overwhelming! 

That’s where the 3-2-1 rule comes in, which can provide some order to this chaos, and give us a plan. There are a few pieces to it:

  • Three: There needs to be three copies of the data, the original, plus two copies of it. 
  • Two: The data needs to be stored on at least two different types of media. 
  • One: At least one of these copies should not be stored in the same location as the other two, and should be offsite. 

The goal is to make this as foolproof as possible. This 3-2-1 rule is considered a best practice to make sure that data gets backed up properly, and to minimize any single point of failure of the data backup process.

With the concern that a location can be affected by a catastrophic event, such as a fire, theft or floor, the recommendation is to keep one of the copies offsite. The way that this was traditionally performed was to send a backup tape to a different location. In fact, there were even tape vaulting services that could pickup and store the tapes securely, and some organizations still use this method. However, this is also less than perfect as tapes can go missing on transport or at the storage facility. Also, tape media can degrade over time, especially with exposure to natural elements, and become unreadable.

Going offsite 

Some more modern examples of options to cover the offsite storage need include an external hard drive at another business location, or a memory card kept in a safety deposit box. Scaling this up, some organizations send data to a remote storage facility. There is also the option to use a cloud based storage option, ideally a cloud backup service that once setup, can backup data to the cloud automatically so as the data is generated, it gets backed up without any further user input to make this as seamless and effortless as possible.

Getting the three copies of the data made also represents a challenge. One simple strategy is to consider the copy of the data on the device as the master copy, and also the first copy. Through backup software, the additional copies are made. This can include having an additional copy on a RAID drive, with mirroring of the data on that drive, or through backup software to a Direct Attached Storage (device), such as an external hard drive. The third copy in some strategies cannot be done in real time, as it needs to be on a separate medium, such as the backup tape media discussed above, so that it needs to happen as a distinct step through intervention at intervals. An advantage of using a cloud storage service is that the data can be backed up in real time, to a remote server, making this as a preferred approach.

There is the advantage of keeping the third data copy offsite in case of catastrophe. However, we should also mention the value of the second copy of the data being onsite. This is so it is convenient, and can facilitate a timely recovery without waiting for media to be shipped back, or even downloaded.

Media considerations 

Additionally, the data needs to be stored on at least two different types of media. This is particularly important as organizations often purchase storage in bulk, and when a lot of hard drivers are purchased, there can be drives with similar failure points that were all from the same manufacturer at the same time. While the external hard drive can be used for the second copy, this is why groups turn to a different storage medium, such as the tape drive with removable media, or uploading the data to a business cloud storage provider, either a company owned remote site, or a dedicated cloud storage solution. The latter has the advantage that it can provide the software to upload the data in real time making it simple to install and live with data uploaded on a continuous basis without relying on user intervention that is likely to be another failure point.

A final consideration is to periodically monitor that the backup strategy is working. It is better not to wait until the primary drive failure occurs, to see that the data has been successfully backed up, and can be accessed.

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Jonas P. DeMuro

Jonas P. DeMuro is a freelance reviewer covering wireless networking hardware.