May I ask has anyone consider SATA RAID yet? I seems to be a very inexpensive solution.
All inexpensive SATA RAID solutions are "fake RAID". This includes almost all SATA controlers that are integrated into motherboards and marketed as RAID capable. They are software RAID. Basically, you use BIOS to write some metadata to the disks (configure the RAID), and than you need to use special drivers in OS that will do the actual software RAID stuff. Most of those specialized drivers are slow, unstable, not available for anything but Windows, or all three of previous statements. If you have one of those motherboards and/or controllers, you are far better disabling RAID stuff in BIOS and using standard Linux software RAID drivers (md) or standard *BSD RAID drivers (RAIDframe).
The only reason why would anybody use one of those "fake" RAID stuff is if you have Windows XP Home/Professional installed on the machine. This will give you software RAID support by using special device driver (since native Windows software RAID driver is available only in Server versions of Windows). Basically this is the core reason why those "fake" RAID controlers exist: chipset manufacturers giving you something Microsoft denied to you. This is more or less desktop/home user domain. For servers, there is no advantage of using them (only disadvantages).
All is not dark. There are several companies making real hardware RAID solutions that use SATA disks. 3ware is one of them and seems to be very well supported and popular in Linux community. Device drivers are part of official Linux kernel. Adaptec has some real SATA hardware RAID controlers. Device drivers for some of them are part of official Linux kernel, for others can be downloaded from Adaptec web site. So if you want hardware RAID solution based on SATA disks, that is the only way to go currently. If buying Adaptec, be carefull. The cheap SATA RAID card they sell is software RAID. You need to buy one of the more expensive ones to get hardware RAID.
Also, there's couple of "accelerated SATA RAID controlers" around. Those are software RAIDs too, special device drivers needed, with some accleration done in hardware. People who tested them reported that they are slower than standard Linux software RAID (implemented by md device driver).
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