SMART failure means that the performance of the hard drive is degrading. It is a warning to give you time to back up the data before the hard drive dies completely. The SMART feature of the hard drive is a group of characteristics that are involved with read/write speed, disk speed and other aspects of performance. You may get this message for weeks or even months, but it is still a good idea to back up your data to another location and prepare to replace the hard drive.