Do you need to format the CompactFlash or HardDrive before use?
Yes. Once connected to the interface, I have found Apple System Utilities 3.1 or later (I think that was the last one) to be best choice for formatting. When formatting the partitions 3 and 4 in certain slots, you may run into a bug that exists in both Apple System Utilities 3.1 and Copy II+ (all versions I believe). See this post in my forum for more details on working around this problem.