Exercise 13.4.7: Using the same RAID level 4 scheme as in Exercise 13.4.6, suppose that data disk 1 has failed. Recover the block of that disk under the following circumstances:

a) The contents of disks 2 through 4 are 01010110,11000000, and 00111011, while the redundant disk holds 11111011.

b) The contents of disks 2 through 4 are 11110000, 11111000, and 00111111, while the redundant disk holds 00000001.

Extra info (from the referenced 13.4.6 exercise):

Suppose we are using a RAID level 4 scheme with four data disks and one redundant disk. As in Example 13.9 assume blocks are a single byte.