As you probably know, RAID drives provide a certain amount of redundancy to any data that is stored on them. Typically that means that if a single drive in a RAID fails, the data on it is not lost permanently and can be retrieved from elsewhere.
Unfortunately many people tend to assume that this redundancy can be used as a ‘backup’. While it is true that your data will be ‘backed up’ across the drives in a RAID, it would be risky to assume that it is the same thing as an actual backup.
Mirrored Data Will Be Altered Immediately
The main problem with relying on a RAID drive as a backup is that it immediately ‘mirrors’ your data cross your drive. As much as that may sound like a good thing for a backup, it actually isn’t – because it means that any changes to your data will be immediately mirrored and all other copies of that data will be altered as well.
In other words, if your data were to be corrupted by software, viruses, or even accidentally deleted – those changes will translate across the RAID drive, affecting the mirrored data as well. Assuming you’re relying on your RAID drive as your one and only backup, you won’t be able to restore it in the way you would from a normal backup.
Simply put when you are creating a backup from your data it should be in a form that is not going to be altered by any changes to the ‘live’ version of the data. That is not what RAID drives do, which is why they should not be used as a backup.
Single Point of Failure
Aside from the issue with mirrored data, RAID drives also suffer from another critical weakness: A single point of failure. At the end of the day a RAID drive is a single unit that is connected to your system and could potentially be affected by any number of issues, including power surges, natural disasters, and so on.
What this means is that any issue of that nature that affects your entire system including your RAID drive and renders it unusable will leave you without a backup. On the other hand if you used backups in the form of cloud storage or even external hard drives that are stored elsewhere – you would not be exposed to this risk.
All in all while redundancies and performance of RAID drives make them more than worthwhile, using them as a backup is not a good idea. The fact of the matter is that compared to other options they leave a lot to be desired and will leave your data exposed to a lot of different risks.
As a rule of thumb it is best to have several backups that are updated regularly, stored in different locations, and checked to verify they are in good working order. By doing so, you will have an additional redundancy that you can use for RAID recovery if anything ever affects the data on your RAID drive. Hopefully now that you realize why RAID drives are unsuitable to act as a backup, you can explore other options and find a more reliable solution that can give your data the protection it needs.