Chapter 38, homework/file-raid/README.md

RAID-1:

 for even-numbered logical blocks, the RAID chooses the even-numbered disk in the pair;
 the odd disk is used for odd-numbered logical blocks. 

should be:

 for even-numbered offsets, the RAID chooses the even-numbered disk in the pair;
 the odd disk is used for odd-numbered offsets.

See raid.py line 231:

                if off % 2 == 0:
                    self.doSingleRead(disk1, off, True)
                else:
                    self.doSingleRead(disk2, off, True)