1. Why do many file systems require that a file be explicitly opened with an open system call before being read?
2. Compare the bit-map and hole-list methods for keeping track of free space on a disk with 800 cylinders, each one having 5 tracks of 32 sectors. How many holes would it take before the hole list would be larger than the bit map? Assume that the allocation unit is the sector and that a hole requires a 32-bit table entry.