Save your data - from bells and whistles.

For several years now, lots of computer systems (and motherboards from which to build them) have been supplied with a feature known as RAID support. RAID is (currently) the acronym for Redundant Array of Independent Disks. (The "I" used to be "inexpensive", but that's been changed to reflect the fact that some technobabble purveyors have found that peddling very pricey RAID setups is profitable indeed.)

Losing your computer's data is a bad thing.  Lots of people rely on regular backups to minimize the amount that vanishes when a hard drive (or whole system) gets toasted, but sometimes that's not considered good enough.  A different approach is the multiple-hard-drive solution known as a RAID.  When it works properly, it reduces downtime for recovery from a single drive failure to near zero, and permits you to simply keep working uninterrupted.  (For a full system failure, it's still vulnerable to problems; that's why even a RAID doesn't make real backups unnecessary.)

On the surface, some of the implementations of RAID look like a really good idea, particularly the simple RAID1 version; it appears to just create and maintain a full-time backup of one disk on another identical disk. And if that were the case, it would be laudable indeed.

Unfortunately, that's not the case. The hardware used to create each of the RAID versions causes the data format of the drive(s) to be changed in a manner that makes it difficult or impossible for the drive to be accessed with just an ordinary controller. For RAID version 0, and for versions 2 through 6, the advisability of using the scheme is even worse; they not only change the format, but they don't even store all of the data together; it gets split up and scattered, rendering the process of recovery far more difficult if something serious goes wrong.

An extensive description of the seven principal types of RAID is available over at Wikipedia, but the bottom line is pretty simple; using RAID increases the complexity of your data storage, and almost always makes recovery harder if you have certain types of hardware failure. For some types of RAID, recovering data after a *single* disk failure becomes easier - perhaps even trivially simple - but as you increase complexity, the number of things that can fail goes up, so the chances that there will be a failure of some sort increase with it - and no RAID can save you from the effects of the operating system going nuts due to a virus or a badly written program, and essentially all hardware-based RAIDs will make your data inaccessible if the controller fails.

All things considered, unless you really, really need either full-time continuous backup or the small increase in performance of a "striped set", even RAID1 is probably not a good idea. The possible exception is in using the RAID capabilities that were built into certain versions of Windows itself; a RAID1 setup done that way is generally as safe as a single hard disk, and provides added protection against data loss due to sudden failure of one of the two drives.

The main reason why I'm posting about this is that apparently, some of the system builders have been shipping machines that have their drives set up using RAID0 from the factory, without providing a Windows reinstallation CD to allow the buyer to convert the machine back to conventional drive formatting. Sometimes this is done to allow the system builder to advertise a unit with what appears to be a huge single drive when in fact it is equipped with two smaller ones that just show up in Windows as a single unit because of the RAID setup. When shopping for a new or refurbished system, it appears that it's wise to ask about these issues. If the machine has only one actual physical hard disk, it's not an issue; any RAID requires at least two drives. But if the box has multiple drives, or an unusually large one, it's wise to make sure to ask about how that's been done - and whether there's a Windows reinstallation CD included.