In relation to the defragmentation idea, allow for compact -c to actually ADD white space. This can help to ensure that the database can have some "room for growth" and alleviate some disk concerns.
Classically, disk saturation (thrashing caused by page faults or long disk queues) are the main cause of poor server performance. Even in the most intelligently designed systems, the recommended standard tasks (compact, updall, stats etc) are culprits for high disk usage.
Intrinsic fo the philosophies of running high-intensity tasks ...