Finally, one can determine the layout of chunks to disks with the following code. The basic idea

Question:

Finally, one can determine the layout of chunks to disks with the following code. The basic idea is to select N random patterns, and to exhaustively read together all pairwise combinations of the chunks within the pattern.

After running this code, you can report the measured time as a function of a and b. The simplest way to graph this is to create a two-dimensional table with a and b as the parameters, and the time scaled to a shaded value; we use darker shadings for faster times and lighter shadings for slower times. Thus, a light shading indicates that the two offsets of a and b within the pattern fall on the same disk.
Figure 6.28 shows the results of running the layout algorithm on a storage system that is known to have a pattern size of 384 KB and a chunk size of 32 KB.
a. How many chunks are in a pattern?
b. Which chunks of each pattern appear to be allocated on the same disks?

Figure 6.28 Results from running the layout algorithm of Shear on a mock storage system.

Figure 6.29 A storage system with 4 disks, a chunk size of four 4 KB blocks, and using a RAID 5 Left-Asymmetric layout. Two repetitions of the pattern are shown.
c. How many disks appear to be in this storage system?
d. Draw the likely layout of blocks across the disks.