Redundant Array of Inexpensive Discs (RAID) is a technology thatuses multiple ha

Question

Redundant Array of Inexpensive Discs (RAID) is a technology thatuses multiple hard drives to increase the speed of data transferand provide instant data backup. Suppose that the probability ofany hard drive failing in a day is 0.001 and the drive failures areindependent.
(a) Suppose you implement a RAID 0 scheme that uses two harddrives each containing a mirror image of the other. What is theprobability of data loss? Assume that data loss occurs if bothdrives fail within the same day. (b) Suppose you implement a RAID 1 scheme that splits the dataover two hard drives. What is the probability of data loss? Assumethat data loss occurs if a least one drive fails within the sameday.
(a) Suppose you implement a RAID 0 scheme that uses two harddrives each containing a mirror image of the other. What is theprobability of data loss? Assume that data loss occurs if bothdrives fail within the same day. (b) Suppose you implement a RAID 1 scheme that splits the dataover two hard drives. What is the probability of data loss? Assumethat data loss occurs if a least one drive fails within the sameday. (a) Suppose you implement a RAID 0 scheme that uses two harddrives each containing a mirror image of the other. What is theprobability of data loss? Assume that data loss occurs if bothdrives fail within the same day. (b) Suppose you implement a RAID 1 scheme that splits the dataover two hard drives. What is the probability of data loss? Assumethat data loss occurs if a least one drive fails within the sameday.

Explanation / Answer

a) P(RAID 0 scheme you lose data ) = P(failure of 1st harddrive ) *P(Failure of second hard drive) = 0.001*0.001 =10-6 .
b) P(RAID 1 scheme you lose data) = P(At least one drive fails)
=1-P(no drive fails)
= 1- P(drive 1 doesn't fail)*P(drive 2 doesn'tfail)
= 1- 0.999*0.999 = 0.001999
Hope this helps. Feel free to ask for anyclarifications.

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