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Controller Requirements

RAID levels differ in terms of the controller required to implement them. In general, simple controllers implement simple RAID levels, while more complex RAID levels require more sophisticated (read: expensive) controllers. Some levels don't require a dedicated controller at all, functioning acceptably using operating system or other software to manage the array (albeit at a performance price).

The simplest RAID levels, often supported by software RAID or low-end controllers, include RAID 0, RAID 1, and RAID 0+1 or 1+0 (though many low-end controllers only support one or the other, not both.) Some lower-end controllers include support for the popular RAID 5 level, and so do some software RAID implementations, but at a rather severe penalty in terms of performance and advanced features. RAID levels 3, 4, 6 and 7, and the other more esoteric multiple RAID levels such as RAID 53 and RAID 30, usually require more capable controllers. RAID 2 is complex enough that it requires special, proprietary hardware; it has for this reason all but disappeared from the market.

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