How do I differentiate "fake RAID" from real RAID?

The Ubuntu wiki page on FakeRaid says the following:

[A] number of hardware products ... claim to be IDE or SATA RAID controllers... Virtually none of these are true hardware RAID controllers. Instead, they are simply multi-channel disk controllers combined with special BIOS configuration options...

Is there a typical way to identify (from a product specification) whether a motherboard has "real" RAID, or are "real" RAID products generally unavailable to consumers?

Solution 1:

The market for RAID controllers is fairly much consolidated these days. Three broad brush heuristics can be applied:

1. Price
   Take a look at the pricing for genuine RAID cards from Areca, 3Ware, Adaptec and LSI. Anything that is much, much cheaper than these controllers is a 'fake RAID'. Remember, if it's too good to be true it probably isn't.

2. Manufacturer
   There are a fairly limited number of manufacturers these days who actually make true hardware RAID controllers. Chances are that something not made by one of the main manufacturers of such kit is a 'fake RAID'. The main outfits that make RAID controllers are: Adaptec, LSI, Areca, Intel and Highpoint (possibly one or two others that I can't recall off the top of my head).

3. Specifications
   The main outfits that produce RAID cards/controllers will also document the specifications in some detail on their web sites. If you can't find a detailed specification for the card get something you can get such a spec for. Note that not all cards produced by these outfits are necessarily RAID controllers, but the specs on the web site should make this clear.

4. Batteries
   Thanks to sh-beta for pointing this out: Pretty much any hardware RAID controller worth buying will also have the option of a battery backed cache. 'Fake RAID' controllers have no cache RAM, using the machine's main RAM as a cache.

Note that IBM, Dell, HP and other server manufacturers also sell RAID controllers. In many cases these are rebadged components made by Adaptec or LSI.

If you want to buy a RAID controller on the cheap, identify some specific models of appropriate specification from various manufacturers' current and immediately previous generations. Then search for that particular model on ebay and get it secondhand.

Solution 2:

Look for mentions of "Host RAID" or "software RAID". Not all fake RAIDs are labelled with one of those, but it'll catch probably 90% of them. There are very few motherboards with (decent) RAID controllers built-in, though. Your best bet is to buy a decent add-on RAID card, or just use software RAID. It's not much slower (except compared to battery-backed RAID cards, which are a whole other world) and it's a million times easier to manage, and more flexible.