There is a BIG difference:
RAID 0 (known as "striping") basically links each drive in the array as one huge drive. Storage capacity is determined by the smallest drive in the array. That capacity is then applied to format all other drives in the array. If using a 4GB, 6GB, 5GB drive in a RAID 0 array, your system will see one huge drive of 12GB (4GB x 3) versus 15GB. RAID 0 offers double or more performance under sustained data transfers when one drive per IDE port is used. In such a configuration, unlike SCSI, IDE drives are always available to the system. SCSI requires more management of the SCSI bus.
RAID 1 (known as "mirroring") makes and maintains an identical image of data from one drive to a second drive or from multiple drives to a second set of multiple drives. Should one drive fail, the working drive or drive set continues operating. To the system, such an array is still seen as a single drive letter. While RAID 1 is the least efficient use of hard drives to provide data protection (since the user does not see any of the additional storage capacity of the mirrored drives), low-cost IDE makes it acceptable. If performing 1-to-1 mirroring with two 4GB drives, the system only sees one 4GB drive. IDE RAID 1 represents a significantly lower cost than SCSI RAID 1.
Lars Coleman
http://home.earthlink.net/~larscoleman