RAID stands for Redundant Array of Inexpensive Disks. It is a way to virtualize multiple, independent hard disk drives into one or more arrays to improve performance, capacity and reliability. The RAID can be implemented either using a special controller (hardware RAID), or by an operating system driver (software RAID).
Hardware RAID is dedicated processing system, using controllers or RAID cards to manage the RAID configuration independently from the operating system. The RAID controller does not take processing power away from the disks it manages. Thus, more space and speed can be used to read and write data. It can work on any operating system. Replacing failed disk is simple – Just plug it out and put in a new one.
As hardware RAID requires additional controller hardware, the cost is higher than software RAID. If your RAID controller fails, you have to find a compatible one to replace in order to get the RAID system to perform the way you set it up.
Unlike hardware RAID, software RAID uses the processing power of the operating system in which the RAID disks are installed. The cost is lower because no additional hardware RAID controller is required. It also permits users to reconfigure arrays without being restricted by the hardware RAID controller.
Software RAID tends to be slower than hardware RAID. Since some processing power is taken by the software, read and write speeds of your RAID configuration, along with other operations carried out on the server can be slowed down by it. Software RAID is often specific to the operating system being used, so it cannot generally be used for partitions that are shared between operating systems.
Replacing failed disk in the software RAID is a bit more complex. You have to firstly tell your system to stop using the disk and then replace the disk.
Software RAID vs Hardware RAID: Which One Should You Choose
Choosing between software RAID and hardware RAID depends on what you need to do and cost.
If your budget is tight, and you are using RAID 0 or RAID 1, there will be no big difference between software RAID and hardware RAID. If you need top performance while using a compute-intensive RAID 5 and RAID 6, you should go for a hardware RAID, because software RAID can really hurt performance. Moreover, esoteric RAID levels such as RAID 10 are usually not supported by software RAID. Hardware RAID is required in that case.
All in all, hardware RAID costs more than software RAID, but offers better performance and free you from the limitations of software RAID, giving you more flexibility in the way it is used and the types of configurations. If your budget allows, hardware RAID is definitely the way to go.