Paul,
You might want to consider some things before going w/ RAID 1.
Exerpted from Wickipedia for you, a few things...
RAID 1: Mirrored set without parity. Provides fault tolerance from disk errors and single disk failure. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing. Array continues to operate so long as at least one drive is functioning.
RAID 5: Striped set with distributed parity. Distributed parity requires all but one drive to be present to operate; drive failure requires replacement, but the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. The array will have data loss in the event of a second drive failure and is vulnerable until the data that was on the failed drive is rebuilt onto a replacement drive.
RAID 1+0 (otherwise known as RAID "Ten"): mirrored sets in a striped set (minimum 4 disks; even number of disks) provides fault tolerance and improved performance but increases complexity. The key difference from RAID 0+1 is that RAID 1+0 creates a striped set from a series of mirrored drives. In a failed disk situation RAID 1+0 performs better because all the remaining disks continue to be used. The array can sustain multiple drive losses as long as no two drives lost comprise a single pair of one mirror.
Bert uses RAID 5. I am using RAID 10 (1+0).
These types of RAID provide a more robust redundancy environment that RAID 1. Most people will not use RAID 1, rather the most common array is RAID 5.
