one way to use contiguous allocation of the disk and not suffer from holes is to compact the disk every time a file is removed. Since all files are contiguous, copying a file requires a seed and rotational delay to read the file, followed by the transfer at full speed. Writing the file back requires the same work. Assuming a seek time of 5 msec, a rotational delay of 4 msec, a transfer rate of 8 mb/sec, and an average file size of 8 KB how long does it take to read a file into main memory then write it back to the disk at a new location? Using these numbers, how long would to take to compact half of a 16GB dosk?

It depends on where the holes are and how much of the 8 GB half is taken up by files.