Software RAID implements the various RAID levels in the kernel disk (block device) code. It offers the cheapest possible solution, as expensive disk controller cards or hot-swap chassis [1] are not required. Software RAID also works with cheaper IDE disks as well as SCSI disks. With today's faster CPUs, Software RAID outperforms Hardware RAID.
The Linux kernel contains an MD driver that allows the RAID solution to be completely hardware independent. The performance of a software-based array depends on the server CPU performance and load.
To learn more about Software RAID, here are the key features:
Threaded rebuild process
Kernel-based configuration
Portability of arrays between Linux machines without reconstruction
Backgrounded array reconstruction using idle system resources
Hot-swappable drive support
Automatic CPU detection to take advantage of certain CPU optimizations