This hard drive is a member of the Grenada family of Seagate hard drives. They are so far the family with the highest failure rate in history. The 3Tb version of your drive (model ST3000DM001) had about 40% fail in just a few years. They're actually in a class action lawsuit over the 3Tb version.
As to your 2Tb one, those had about 60-70% the number of failures as the 3Tb ones had, but only due to the fact that they have one less platter and two less read/write heads to potentially fail.
If your drive isn't clicking yet, and still sounds to be spinning normally, a data recovery company can likely patch the firmware and extract the data quite easily still. I can't speak for other labs, but here we charge a flat $450 for this service so long as the drive comes in before any of the heads totally fail.
But, if you push your luck and keep trying things to get the data back yourself, it's going to totally stop responding and eventually start to click when the heads die. What's currently happening is that the drive is getting stuck in a busy state while trying (and failing) to reallocate bad sectors using spare sectors. This function was totally botched in the firmware programming, and they never accounted for how quickly these drives would develop bad sectors. So the more bad sectors develop, the more it gets stuck busy due to these background processes.
Edited by DataMedic, 21 May 2018 - 10:07 AM.