RAID (redundant array of independent disks) is a storage technology that combines multiple disk drives into a logical unit. It is being used for may years in servers and data centers. For the last few years it has become popular in desktop computers.

In servers it is used mainly for redundancy. That means if one drive fails it can be replaced without loss of data. There is enough data on the other disks to rebuild the data on the new disk. Depending on the setup, RAID can be used to increase performance as well redundancy. There are different levels of RAID. I am not going to explain all the levels in this article.

What I am going to explain when RAID should be or should not be used.

As I have mentioned before, servers in computer rooms and data centers are always using a RAID setup. Those servers have usually build in high end RAID controllers. Those controllers are usually very expensive. Sometimes software RAID is being used in low end servers. Software RAID is build into the operating system like Windows or Linux.

The trend for the past few years is, fitting cheap RAID controllers into desktop computers.That where I can see the problem. Those cheap RAID controllers are not real RAID controllers, but standard drive controller chips with special firmware and drivers. They are usually build into the motherboard. There are using the main CPU for the processing. They are also called fake RAID.

Apart the performance penalty with those controllers, the main problem is, there is no standard between different controllers. For example, a system using this kind of RAID stops working and the motherboard needs to be replaced. The original motherboard is no longer available. A different motherboard may not be able to read the existing RAID. That means the data on the disks cannot be read, in other words a complete loss of data.

My Conclusion

For the above mentioned reason I would advise against RAID in desktop computers.     On servers on the other hand I would use RAID with a dedicated high end RAID controller. On low end servers and NAS boxes I would use the software RAID build into the operating system.

A RAID setup is no substitute for a proper backup plan. RAID protects against disk drive failure but not against data corruption, accidental deletions of files, viruses, or physical destruction of the unit.