$1.(32\backslash \%,4\backslash \%$ each$)$ Short Questions. Keep your answers short and precise.

$($a$)$ Explain what is the vendor lock$-$in problem in cloud computing. State one possible way to solve the vendor lock$-$in problem.

$($b$)$ Suppose that HDFS configures the block size as $4$ GiB $($instead of the default block size$).$ Explain how it possibly improves or degrades the write performance.

$($c$)$ Explain how Spark improves the performance of Dijkstra's algorithm in MapReduce.

$($d$)$ Load rebalancing may not be effective in BigTable deployment. State two reasons.

$($e$)$ Under the CAP algorithm, if we ensure that both C and P hold, what does it mean? Why can't we ensure that A holds in this case?

$($f$)$ Dropbox uses server$-$side deduplication instead of client$-$side deduplication. State one advantage and one disadvantage.

$($g$)$ Suppose that Facebook's Haystack keeps four replicas for each photo for high fault tolerance. What is the number of I$/$Os to delete a photo? Derive your answers.

$($h$)$ Tail latencies can be reduced by sending hedged requests or tied requests. State one advantage and one disadvantage of sending hedged requests instead of tied requests.