Linux

1. Run filesystem check on all partitions (e2fsck /dev/sda{1,2,3,4,5} )
   
2. Check hard drive S.M.A.R.T data (smartctl -a /dev/sda )
   
3. Kick off S.M.A.R.T test (smartctl --test=short /dev/sda )
   
4. Check hard drive S.M.A.R.T data (smartctl -a /dev/sda )
   
   

If the data is precious "dd" each partition onto another drive before doing this.