Software mdadm RAID advantages:

  • mdadm is mature and free software, well documented with a lot of industry experience.

  • Quality: mdadm is vigorously tested by many and available on all GNU/Linux distributions. Always evolving it is getting better and better all the time.

  • Independence from hardware vendors. mdadm RAID can be easily moved to different hardware.

  • Compatibility: mdadm works with virtually any hardware, no vendor lock-in. Freedom to use any HDDs, any HDD controller or mixture of controllers/HDDs. mdadm works on nearly all HDD controllers (RAID or non-RAID) supported by Linux kernel.

  • Cost-effective / Better value for price: mdadm can do more than any hardware RAID for free. No need for expensive controller, memory, battery or RAID6 functionality in hardware.

  • Easy upgrade: upgrading mdadm is trivial comparing to flashing BIOS of hardware RAID controller.

  • Features: there are many features that hardware RAID controllers do not have [readonly,bitmaps,write-mostly,write-behind etc.].

  • Flexibility far beyond any hardware RAID controller (online re-shaping, growth, global or per-array rebuild speed control etc.).

  • Performance: modern multi-core CPUs always outperform RAID chips.

  • Monitoring: periodic array checks, emailing array status if not OK, does not obstruct S.M.A.R.T. monitoring.

  • Good investment of time: mdadm managing skills are of much greater value than experience with any particular brand of hardware controllers as those skills are portable and not specific to hardware or blend of GNU/Linux distributions.

Software mdadm RAID disadvantages:

  • Can't boot operating system from RAID-5/6.

See also