Sign of Hard Drive Failure

How to know that the hard drive on the laptop have been failure or will failure soon. This is very important so that we preparing to recovery all files in the hard drive before real failure. Because, as we know that we very difficult to recovery the files in the hard drive failure.
What is the signs of hard drive failure :
1. Laptop running slow. If the laptop keyboard no problem, and no viruses or any other problems but the laptop running very slow, difficult to open one of the drive, this mean the hard drive get the problems.
2. If the laptop won't booting. Or need so many times to loading the boot file.
3. You can hear the half aloud from inside of the laptop a like " krekkk " during open the new application or when finished normally shut down the laptop.

If you meet the problems a like these you should take all files from the laptop to other portable hard drive or flask disk, and you can try to repair the hard drive or replace this.