RAID levels 0, 1, 3, and 5 are the RAID implementations typically used in hardware-based solutions.
Hardware-based RAID uses an intelligent drive controller and a redundant array of disk drives to protect against data loss in the event of media failure and to improve the performance of read and write operations. A disk array is a collection of multiple disk mechanisms that are coordinated by an intelligent controller, and is an effective disk-storage solution for SQL Server computers.
Hardware-based RAID levels 1-5 automate redundancy and fault tolerance at the hardware level. All levels (0-5) incur no overhead on the system processor. Individual data files are typically spread across more than one disk. It is possible to implement a hardware-based RAID solution that provides your system with seamless, non-stop recovery from media failure.
In general, hardware-based RAID offers performance advantages over use of Windows NT software-based RAID. For example, you can improve data throughput significantly by implementing RAID level 5 through hardware that does not use system software resources. In either configuration, this is accomplished by using more disks at a given capacity as compared to a conventional storage solution. Reading and writing performance and total storage size can be further improved by using multiple controllers.
Depending on the configuration, hardware-based RAID generally provides very good performance. It also makes it much easier to manage multiple disks, by essentially allowing you to treat an array of disks as one disk. You may even be able to replace a failed drive without shutting down the system. The disadvantages of a hardware-based solution are that it can be very expensive and may lock you into a single-vendor solution.
For more information about implementing hardware-based RAID, contact your hardware vendor.