According to some, all HW RAID is superior to SW RAID. Others claim that the RAID support provided by a cheap motherboard such as this ASUS MB is not really true HW RAID and that using Linux SW RAID is superior. Trying to sort this out I found this site, claiming that the RAID control provided by these kinds of motherboards is NOT real HW RAID control, but rather SW RAID provided by the BIOS.

I am about to set up a file server with two disks in a RAID 1 configuration and I am wondering whether I should buy a MB with "HW RAID controller" or whether I am better off using Linux SW RAID. Performance is a non-issue; file integrity, security and long-term recovery is everything. Buying a real RAID controller card is not within my budget. If the fake HW RAID is the better choice, can I get it to work under Linux?

Best regards
Tord Strømdal, Linux Newbie

for this purpose, and based on your criteria of cheap but flexible, I would recommend Linux software raid. It is very easy to manage and recover even if the motherboard you use dies. You can just move the drives to a new system, plug them in and your data will work.

With bios controlled raid, I have occasionally found that unless you can replace the motherboard with the exact same unit, your data may be lost.

If this is true, there's no competition.

Software RAID has the advantage that you can reassemble your RAID array in the case of a hardware failure.

Hardware RAID has the advantage of being able to perform the RAID funtions without using and CPU. CPU usage isn't a very big deal on RAID 0 or 1, but on something with parity information (RAID 4,5,6, etc.), this can be a huge issue. Your software RAID array can and will steal substantial amounts of your CPUs.

I generally prefer hardware RAID to software RAID, but I find a RAID controller is worth the money when you're dealing with servers.

There's a lot of personal preference when choosing software vs. hardware. Usually, the user is just running RAID 0, 1, 10, or 0+1, so CPU usage is minimal in software RAID. Then you need to identify what you feel is more likely to fail: two HDDs (or whatever is one more than your RAID array can tolerate), or your mobo/raid controller. If you run something like RAID 5, you'll almost certainly want hardware RAID if you expect to be using much CPU elsewhere on your system.

That last comment will probably start a flame war. Oh well.

-TheDirtyScreech-

No flames. But, I tried a network attached RAID storage, that was based on Linux software RAID. It was as slow an molasses. I'm currently in the process of re-building my server, with an old LSI IDE raid card that cost me $70. Yeah, I know IDE RAID 'aint the fastest in the world, but I'm more interested in the redundency than the speed.

Cheers.

Thank you, TheDirtyScreech, for your informative answer. The more I read, the more I am leaning towards SW RAID.

The main purpose of the server is to make sure that my files do not disappear. Recovery from a failure (disk crash or controller malfunction) is by far the most important factor. If a disk crash results in me shutting down the server until I've bought a new HDD, that's OK. But losing the entire RAID array because of a MB failure is not acceptable.

I will "only" be running RAID 1 on the server, and the server will be a dedicated file server with only one other task: domain controller for a small home network. If the RAID operations hog CPU cycles it's something I can live with.

If you'd like to read more about this (future) system (and perhaps help me with more input), please take a look at this post: http://www.linuxquestions.org/questi...d.php?t=575869

Best regards
Tord Strømdal