Using flash drives -- or "USB keys" since they are often on a key ring -- as part of a RAID array is possible in the same way that one might use standard hard drives in a RAID array. RAID stands for "redundant array of inexpensive disks." It is a method most commonly used to make automatic backup copies of files by making one disk make an exact copy of a second disk simultaneously. RAID can also be used to "span" disks, allowing two to operate like they were one larger disk. Both features are available in Windows 7.
Attach your USB drives to your computer. Click "Take no action." Click the "Start" button and click "Computer." Note the drive letters for your two USB keys/drives.
Click the "Start" button, and then right-click "Computer." Select "Manage." Click "Storage" and then "Disk Management." A window appears listing all your available hard drives, including USB keys/drives.
Right-click the first USB drive from which you would like to create a RAID partition. Select "Delete volume." This will create an "unallocated drive." Do the same for the second USB drive. Note the numbers of each drive -- they are labeled as "drive 1," "drive 2," and so on.
Right-click the first USB drive again. Select "New Mirrored Drive." You will be asked which drives you would like to mirror. Note that this drive is already listed under "Selected." Click the second USB drive and click "Add."
Click "Next." You will be asked if you are certain that you want to continue and you will be told that this process will create a single drive which is "mirrored," in essence allowing your two USB drives to copy each other exactly. Click "Yes." The new RAID drive is created.
Things You'll Need
Windows 7 Professional, Enterprise or Ultimate
Two USB drives – exact same size (different sizes if creating spanned disk)
If you would like to create a “spanned” drive, where more than one drive is combined into one giant drive, select “New Striped drive” in step 4, and then continue as in the instructions. Instead of being told you are creating a mirrored drive, you will be told you are creating a striped drive, but the experience is exactly the same. You can also choose “New Spanned drive,” which is safer regarding data integrity, but will give you poorer performance.
Never unplug one of your USB keys while the computer is on. Be sure that you plug both of them in before turning the computer on if you remove them when the computer is off. Failure to do so may cause your RAID drive to fail (though your data should be safe).
Note that your USB drives will both be erased during this process. Be sure they are empty, or backed up, before proceeding.