RAID 5 – Redundant Stripe Set. A RAID 5 array is most useful for high read files such as the database files (mdf and ndf files) and file shares. It is the most cost-effective, high-speed RAID configuration. With a RAID 5 array, there is a performance impact while writing data to the array because a parity bit must be calculated for each write operation performed. For read performance, the basic formula is (n-1)*o where n is the number of disks in the RAID 5 array and o is the number of I/O operations each disk can perform. Note: While this calculation is not perfectly accurate, it is generally considered close enough for most uses. A RAID 5 array can survive a single drive failure without incurring any data loss.