RAID stands for Redundant Array of Independent Disks. In general, RAID takes advantage of multiple hard drivers to promote reliability, capacity, and performance.
If you purchased RAID for your dedicated server, it will create an exact copy (or mirror) of all of your data on two disks. If you experience a drive failure on one of your disks, your other disk will continue to operate. This protects you from data loss and server downtime.
RAID can also improve your server's performance by providing data on your hard drives more quickly.