Configuring two or more hard drives in a RAID setup can speed up hard-drive performance and provide automatic protection against data loss from a drive failure. RAID used to be expensive, hard to implement, and limited to businesses with dedicated IT departments, but now even the motherboards on most budget PCs support it, making RAID easier to install and well within the price range of most tech-savvy PC users.
What level of RAID do I want?
RAID comes in a number of flavors--or levels--that offer data protection, enhanced hard-drive performance, or both. In addition to the seven core levels of RAID (RAID 0 through RAID 6), you'll encounter a slew of variants and combinations. Following are the RAID levels you'll find on affordable, consumer-level RAID adapters.
RAID 0: This setup increases hard-drive performance by spreading, or striping, data over two drives so that it can be read and written more quickly. Unfortunately, such an array provides no data protection--in fact, it actually increases the chances of data loss since the failure of any one drive in the array results in the loss of all data stored on both drives. RAID 0 setups are standard on high-end gaming and graphics PCs, and provide a measurable albeit modest performance boost for games, graphics applications, and other hard-disk-intensive programs.
RAID 1: A RAID 1 setup protects data from a drive failure by simultaneously writing data to two hard drives: a master drive and a backup (or mirror) drive. Since the second drive carries an exact copy of the first, it provides no usable storage capacity. RAID 1 offers no gain in drive performance.
RAID 5: Though you get both faster disk performance and data protection from this setup, it requires a minimum of three hard drives. Instead of using an entire hard drive as a backup, RAID 5 spreads redundancy information--called parity bits--across all of the array's drives, increasing the proportion of usable disk space. A three-drive RAID 5 setup presents two drives' worth of storage capacity, a four-drive array offers three drives for storage, and so on. If one of the drives fails, the data content of that failed drive can be recalculated from the parity bits on the surviving drives and written to a new, replacement drive.
RAID 1+0 or 0+1: Some adapters support combinations of RAID 0 and RAID 1, which provide both data redundancy and increased disk performance. Since these nested implementations are not standardized, names and functionality can vary from vendor to vendor. RAID 10, RAID 1+0, RAID 01, and RAID 0+1 are all common names for nested arrays. These RAID combinations require a minimum of four hard drives.
What hardware do I need to set up RAID?
RAID controller: You probably already have a RAID adapter in your PC; many midrange and high-end motherboards come with a built-in RAID controller. Check your PC or motherboard documentation to find out if your motherboard supports RAID (and if so, which levels it supports), and consult any specific installation instructions.
If your PC doesn't have RAID support built in, you'll need an adapter card. Adapters supporting RAID levels 0, 1, 10, and sometimes 5 can be found online for around $100 or less. Adaptec and Promise offer a wide selection of RAID adapters.
Two or more hard drives: In theory, most RAID 0 setups can be configured with hard drives of different sizes from different manufacturers. In practice, you'll save yourself a lot of time and grief by building your array with identical hard drives--meaning drives of the same make, model, and size. At the very least, use two drives from the same manufacturer.
Floppy drive: If you plan to install Windows XP on your new array, you will need a floppy disk with your RAID adapter's Windows drivers, and a floppy drive to read it--Windows' installation won't install the drivers from an optical drive. Thankfully, this incredibly annoying quirk of Windows XP goes away in Windows Vista.
Tools: You need a small, nonmagnetic Phillips screwdriver to remove and replace the fastener screw that secures the adapter card to the PC chassis, as well as to install any new hard drives. You'll also want a simple grounding strap that attaches to your wrist; look for one at your local computer store for less than $15.
How do I install and configure a RAID setup?
The exact procedure for installing any RAID adapter varies from manufacturer to manufacturer and even from model to model, so thoroughly read all of the documentation accompanying your adapter (or motherboard if the adapter is built in) before starting the installation process. Still, the overall procedure is generally the same for all RAID adapters:
- Install the adapter card and hard drives in your PC.
- Configure the adapter card and hard drives in the PC's or card's BIOS.
- Install the controller's drivers in Windows.
Installing the RAID Adapter and Hard Drives
Here's how to install a RAID adapter card in your PC. If your motherboard already supports RAID, skip to "Configure the Adapter in BIOS" below.
- Unplug your PC and position the case so that you can comfortably reach into the interior. If you have a tower case, you'll find installing an expansion card easier if you lay the case on its side.
- Protect your PC's delicate circuits from static electricity charges on your body by properly grounding yourself. If you don't have the patience or time to buy a grounding strap, at least make an effort to ground your body by touching a metal faucet, a pipe, or even your PC's case before touching the inside of your PC or any component.
- Locate an open PCI or PCI Express expansion slot and remove the cover bracket that blocks the slot's access port on the back of the case. Typically, a single screw secures the bracket.
- Remove the adapter card from its packaging, handling the card by its edges; avoid touching the chips and circuitry on either face of the card.
- Align the adapter card's connector with the expansion slot and gently but firmly push down on the top edge with even pressure until the card is securely seated in the slot. Secure the card to the chassis with the existing screw or other clamping mechanism.
- Once the card is installed, install and connect the hard drives to be used in the array. See "How to Install a New Hard Drive" for instructions.
- Reassemble the PC and power it up.
Configure the Adapter in BIOS
Each RAID adapter has a firmware configuration program, unique to that make or model, that lets the user select the type of RAID array to install and choose which hard drives to include in the array. Refer to your adapter or motherboard documentation to guide you thorough the specific installation steps for your adapter.
- Typically, you launch the program by pressing Ctrl-R, Ctrl-A, or some other key combination during the PC boot process. Watch the screen for a prompt, or check your adapter's documentation.
- You may also have to launch your PC's CMOS setup program and configure your SATA hard drives for use in a RAID configuration.
- When asked to select a stripe size or chunk size for a RAID 0 or RAID 5 array, select the default size. Playing with these settings may increase performance for users with plenty of time and energy to experiment.
Install the Adapter in Windows
If you are installing Windows XP or 2000:
- Carefully watch the bottom of the screen at the very beginning of the setup process for the prompt, and press F6 if you need to install a third-party SCSI or RAID driver. Be quick: You have only a few seconds to press F6 and launch the installation process.
- Wait for the screen that says 'S=Specify Additional Devices' in the lower-left corner. Press S.
- When prompted, insert the floppy disk with the adapter's drivers into the floppy drive and complete the driver installation. Once that's done, Windows should continue the Windows installation routine.
