First, RAID is not a backup solution – always employ disaster recovery options.
I field queries about – RAID 1 (mirror) software versus hardware solutions from time to time. Both have their advantages and disadvantages. Some say adding a hardware RAID controller introduces another point of failure, but the most popular reason by far to use software RAID is cost. If you do go with hardware RAID, make sure that card is compatible with your motherboard.
With BIOS (basic input output system) RAID – you may encounter a few quirks. Essentially, it’s a poor man’s version of software RAID. Motherboards do fail, so if yours gets fried, you’ll probably have to replace it with a similar board. Taking a mirrored drive to another system won’t work if that system can’t track the drive’s volumes.
Do you want – redundancy or performance? Most of us would prefer both. I think software and hardware RAID solutions work fine for redundancy, but hardware RAID holds the advantage in performance, especially if your server is database intensive.
There are other perks to – hardware RAID solutions as well, like notification of specific drive failures. Software RAID solutions typically have problems identifying bad drives, and normally do NOT support hot swaps. The most obvious drawback to software RAID is that it uses cycles from your CPU to manage the array, and while this isn’t quite so bad in RAID 1, it can significantly slow down your server in RAID solutions that involve striping with parity.
For those of you who use multiple operating system environments, hardware RAID is the way to go. If you set up RAID using a specific operating system, only that operating system can (normally) access that array.
Software boot volume limitations – since the operating system has to be running to enable the array, (obviously) the operating system cannot boot from the array.
My recommendation – do what makes sense for your pocketbook and priorities. Software RAID is definitely less expensive, but has performance drawbacks. Hardware RAID costs more, but is feature rich and generally worth the investment.