happycat59 (3/25/2011)
I believe that the data is actually stored on 3 disks...2 have the actual data and the 3rd has the exclusive OR of the other 2 disks. Using this, if you loose any one of the 3 disks that store the data you are after, the other 2 have enough information to give to retrieve the data. This basic pattern is used regardless of the number of disks in the array. When there are more than 3 disks, each chunk of data is still stored on 3 of the disks. The controller manages the allocation of disk space to ensure that all disks on the array are utilised.
No chunk of data is ever stored on 3 discs. In a 3 disc array each bit is stored on one disc, and the XOR of each even numbered bit and the next following bit is stored on whichever disc neither of those bits was stored on.
I think anyone guilty of describing your remarkable multi-disc arrangement as with 3-way parity no matter how many drives are used either is thinking of RAID 05 (RAID 0+5) (a really imbecile arrangement, dreamt up by a gentleman who didn't understand what RAID 50 was) or isn't thinking at all.
Tom