4.2 Problem-Solving Tasks (8 marks) 4.2.1 Task 1 (4 marks) Imagine a program that works with data files, where each file consists of fixed-size data records of 256 bytes each. A total of 1,500,000 such records needs to be stored on disk. Assuming the disk has 4096 bytes per sector, 63 sectors per track, 90 tracks per surface, and 4 usable surfaces, how many of the following will be required to store all records? (a) sectors (b) tracks (c) surfaces (d) disks 4.2.2 Task 2 (4 marks) Assume that the disk head is initially positioned on track 123 and is moving in the direction of decreasing track number. For the following sequence of disk track requests: 3, 126, 111, 210, 137, 42, 9, 77, 138 (a) Describe or trace the order in which these requests are served based on the following four disk scheduling algorithms: (0) FIFO (ii) SSTE (iii) SCAN (iv) C-SCAN (b) Calculate the average seek length (in terms of the number of tracks traversed) for each of the disk scheduling algorithms. (c) Discuss your attempts for (a) and (b) with your tutor