8. Explain the concept of the mean time to failure, the mean time to repair, and conceptually how redundancy and parallelism help address efficiency and reliability problem in the context of mass storage. 9. Regarding file system links, answer the following questions, (a) Explain how hard links and soft links differ conceptually. (b) Explain how they are differ with respect to i-node allocations. (c) Is possible that a file system tree is no longer a tree, and a cycle may appear when one traverses the file system? Give an example to illustrate your idea. 10. Consider a file system on a disk that has both logical and physical block size of 512 bytes. Assume that the information about each file is already in memory. For each of the following allocation strategies, contiguous, linked, and e indexed answer the following questions, (a) How is the logical-to-physical address mapping accomplished in this system? For simplicity, we assume that a file is always less 512 blocks long. (b) If we are currently at logical block 10 and the last block accessed was block 10, and want to access block 4, how many physical block must be read from the disk