9.3.2. Software RAID

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 [2] are not required. Software RAID also works with cheaper IDE disks as well as SCSI disks. With today's fast CPUs, Software RAID performance can excel against Hardware RAID.
The MD driver in the Linux kernel is an example of a RAID solution that is completely hardware independent. The performance of a software-based array is dependent on the server CPU performance and load.
For information on configuring Software RAID during installation, refer to the Chapter 10, Software RAID Configuration.
For those interested in learning more about what Software RAID has to offer, here are the most important 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

[2] A hot-swap chassis allows you to remove a hard drive without having to power-down your system.