Software RAID - Stripe Your Drives Without Extra Hardware

RAID (or Redundant Array of Independent Disks) is a set of technologies for spreading information across multiple disks. This can be configured to provide increased fault-tolerance, increased performance, or both. Usually this is implemented with special hardware, almost always on SCSI drives.

Linux provides the ability to let the kernel create a "virtual" RAID system, spreading information across multiple disks. It currently supports all major levels of RAID, from Level 0 to Level 5 and Level 0,1. Because it is implemented in software and not hardware, it is generally slower than a hardware-based system, but can be dramatically faster than not having any RAID at all. Also, Software RAID can be implemented on IDE disks as well as SCSI.

For more information, check out the Software RAID HOWTO.