Hardware RAID support in Linux

krizzz · 06-29-2010, 08:02 PM

Hi,

I'm building a Linux based NAS. So far I got two 1TB WDC drives and the mini itx case. I'm debating between getting a mobo with built in RAID controller and getting the mobo and controller separately, as PCI card.
My biggest concern now is the support for hardware RAID on Linux. How does it look like in practice? Should I be looking for specific controller types? Are there any drivers required/available? Is the software for setting it up available?

Any help will be appreciated.

Chris

jschiwal · 06-29-2010, 08:28 PM

The raid that you get builtin with the motherboard is really software raid. Even some sata raid cards use the CPU for parity calculations. According to the README from dban, the only true hardware raid card for sata is by 3ware.

jefro · 06-30-2010, 03:11 PM

I agree, you'd only get any benefit from a true hardware raid array.

krizzz · 07-01-2010, 04:41 PM

Thanks for the priceless info!
3ware controllers cost $170+. I think it's too much for this little home project and I guess I will be just fine with a software mirror. I am still a little confused though... Do I still need to get the motherboard that has RAID in specs or I will be good with anything that has 2 SATA ports? I think the answer is 2 but would like you guys to verify...

jlinkels · 07-01-2010, 06:33 PM

The answer is (2), and even if you have to buy a MB with on-board RAID, don't use it. I experienced troubles booting Linux from such a RAID-ed array. mdadm is your friend.

jlinkels

jefro · 07-01-2010, 07:35 PM

Not even sure if you do get any real benefit from a faux raid controller. I have not seen any modern tests. I'd suspect you would be better off not using it unless it is a real raid. Software raids may be OK for data security but they tend to be poor choices for speed. They may slow down your system. If you want to mirror then any board with any array would work. Just be sure you know how to rebuild a mirror using the boards tools.

krizzz · 07-01-2010, 09:51 PM

Thanks guys, I ordered Atom D510 based board. The CPU is 1.6Ghz dual core which I hope will be enough for the home NAS solution.

jlinkels · 07-02-2010, 07:00 AM

That is a good choice, I am moving more and more to Atom boards myself. For a NAS that is an excellent choice, and it is powerful enough.

jlinkels