Some external hard drives make use of a hard coded sleep mode that kicks in after some time of inactivity, usually between 10-15 minutes. The external hard drive will enter sleep mode and initiate a wake up when new data is requested of the drive. This can be problematic in some circumstances where the user does not want this to happen or where the drive has troubles waking up again.
NoSleepHD is portable and comes with a graphical user interface that can be used to configure some of the program’s settings. The gui can be used to select the external hard drive that should be prevented from going into sleep mode and to define the write interval of the blank text file.
More here.
