Digiliant offers many popular RAID Levels to fit your storage needs.  Below are the standard 3 RAID configurations we recommend depending on the total number of drives in your system:

RAID 0	All the drives will be Striped together.  It offers the best performance of our RAID offerings, but at the sacrifice of Redundancy.  If you choose this level you must have a backup protocol in place because if even one drive fails the entire array will be lost.
RAID 5	Creates redundancy by writing parity information across the drives that allow for data reconstruction should one drive fail.  Along with a data loss of approximately one drive for this data, there is also a slight performance hit due to the extra parity information being written.  An additional option of RAID 5 is to designate one drive as a Hot Spare.  While this means the loss of another drive as available space, if one drive fails then the Hot Spare will activate and rebuild into the array.  Once the bad drive is replaced the new one then becomes the next spare.  For systems with 4 drives we recommend RAID 5 with no spare.  On systems with 6 to 12 drives we recommend RAID 5 with a Hot Spare.
RAID 6	RAID 6 works the same way as RAID 5 with two differences.  The first is that an additional parity scheme is used that creates an extremely high fault tolerance.  The second difference is that RAID 6 also uses one of the drives as a spare, but unlike RAID 5 this spare is built into the array at creation.  Due to this high level of data protection, we recommend RAID 6 on all systems with more than 12 drives.
RAID 10	This level is hybrid that uses creates multiple mirror sets and then stripes them into a larger array.  While performance is good, there is a significant amount of space lost due to the mirror sets.