Spanning allows a file or a volume to be larger than the size of a single disk. This simplifies file service in some operating systems or applications where a single volume of very large capacity is required. Spans are also called arrays or logical drives. Because the probability of a failure is higher than for a single drive, mirroring or parity is frequently added for fault tolerance. If either drive fails, the system continues to work from the other.
Mirrored systems require at least two drives, higher .RAID levels require more than two.
This is the most widely used .RAID level. It is found in Industrial, Manufacturing and Communications systems where performance and minimum downtime are critical. PSI specializes in support for OEMs and VARs needing cost effective, high performance fault tolerant systems. As drives are added, the chance of a drive failure increases. Using parity, missing data can be reconstructed from the remaining data.