Linux software RAID has nothing to do with hardware RAID controllers. You don’t need an add-on controller, and you don’t need the onboard controllers that come on most motherboards.
The RAID devices are virtual devices created from two or more real block devices. This allows multiple devices (typically disk drives or partitions thereof) to be combined into a single device to hold (for example) a single filesystem.
Some RAID levels include redundancy and so can survive some degree of device failure.
Currently, Linux supports LINEAR md devices, RAID0 (striping), RAID1 (mirroring), RAID4, RAID5, RAID6, RAID10, MULTIPATH, FAULTY, and CONTAINER.
Continue reading “RAID in Linux, using mdadm in Linux.”