We study redundancy schemes, namely replication and erasure coding, used in Facebook photo storage.

B$)$ Recall that f$4$ is originally configured with $($n$,$k$)=(14,10).$ Reed$-$Solomon coding in each cell to tolerate four disk failures. Suppose that it now changes the configuration to $($n$,$k$)=(12,8).$ Derive quantitatively how the new configuration changes the per$-$cell redundancy factor and single$-$block repair performance, in terms of percentage of increase or decrease.