Linux & Fake RAID?
 

I was just thinking about getting a new motherboard / CPU from Newegg.com and wanted to know how Linux (Debian / CentOS) handles these on-board RAID controllers that some refer to as 'fake' RAID. I just want to mirror (RAID 1) two S-ATA drives together but not do 'software' RAID from the OS. Has anyone have any suggestions when selecting a motherboard using this on-board RAID controllers?

Linux software RAID is great.

Linux support for fake RAID is a lot trickier to set up. Once it is set up it has at least as much overhead as software RAID. With just Linux there are multiple advantages to software RAID over fake RAID and no advantages of fake RAID over software RAID.

In a dual boot system of Windows and Linux, using the appropriate fake RAID support may make it much easier for Linux to access Windows partitions vs. using simpler software RAID. Without that case to worry about, I doubt fake RAID would ever have been worth even supporting in Linux.

It is much easier to turn off the fake RAID and then use pure software RAID.

You can get some very strong disagreements with no one convincing anyone if you make the comparison between software raid and true hardware raid. But between software and fake, software is just better unless you need to share partitions (maybe drives) with Windows.

In fact, dmraid (the driver for fakeraid) actually uses the software raid drivers in the kernel. Unfortunately, you can't use mdadm commands to do array maintenance - you're limited to using the BIOS. So, like John says, if you're dual booting with Windows, fakeraid might be the answer; otherwise use mdadm.

I just notice in Debian when using software RAID, I always see errors when shutting down or anything that pertains to rebooting the system. It tries to shutdown cleanly and I always see a 'red' failure notice which annoys me. I don't actually know if it's a real error but anytime I see something in red when shutting down and it is an error, it annoys me. It has been this way for Debian since I started using them (Sarge).