I'm using a 2TB Samsung (Model: HD204UI) 3.5 inch hard drive in a Sharkoon QuickPort Duo USB 3 dock, and most of the time it works fine, it's fast, no problems. I use it to back up another external drive with a little app called Backup Buddy, so it's not the end of the world if it dies. I just want to know what this is and if I can fix it. Then sometimes, like right now, I plug it in and it won't show up on the desktop. Its drive access LED is blinking furiously and it's making a lot of noise. It's definitely "doing something" but the OS won't let me access it until it's done with whatever it's doing. During this time, in Activity Monitor, the process called "fsck_hfs" is using 70% of the CPU. I imagine this is related to the HFS partition on that disk. I guess the OS is seeing something wrong with the disk and is trying to fix it. It will do this on other computers, and in other enclosures too. Other WD hard drives I have run fine in the same dock. Once, I noticed that there was a "DamagedFiles" folder on the root of that drive with two tiny unreadable files in it. When I open Disk Utility while it's plugged in but not mounting, Disk Utility refuses to load anything, it just says "Loading Disks" and I can't use it at all, like this: Then eventually (in about 10-20 minutes) the drive stops whirring, fsck_hfs stops taking up 70% of CPU, and the drive mounts on its own and Disk Utility starts working again, reporting no issues. Then a few months later, the issue happens again. What could this be exactly? It seems like a specific file system repair thing that the system is doing. Could it be normal housekeeping? Or is my drive dying physically? Should I try formatting it and starting over with it? Is it possible that there is nothing physically wrong with the disk, but the "Backup Buddy" app I'm using keeps messing something up while backing up? Can anyone recommend another simple incremental backup app (like Time Machine)? Thanks for any help!