I have a 2 TB Western Digital hard drive that is connected to my MacBook Pro for a Time Machine backup. When I plug it in, it is unmounted. After trying to mount it, I get this message:
Also, First Aid fails on the disk:
I am unable to access the contents of the drive to copy it to another, and I need the backups.
MacBook Pro 15”, macOS 10.14
Hi, welcome to the Apple Users Community.
Have you switched out the cables or used and alternate USB port?
Best of luck
Try Console under Applications > Utilities > Console.
It can show if an external drive or any error is detected under the Errors and Faults tab.
If no errors show up, then the problem is not being caused by the device.
Also try to select the ASMT-ASM1156 to run first aid not the named "Back Up" drive in the sub tab.
Ah, have you got access to another computer at all?
You do know the process for disconnecting USB devices on a Mac? Simply turning them off is not good, please see this link for the best process. Please tell me that you haven't been doing that all along even when the drive was working.
Can you confirm what format the drive is?
I think the drive is HFS+, but I’m not sure. I also cannot eject the disk because it is already unmounted. Before it was always plugged in, and I don’t remember when I last unplugged it. I can go try another computer in a few minutes.
Yes, I have tried other ports and other cables. I still can’t mount the drive.
It didn’t repair any errors. I have been disconnecting the drive by shutting off the power.
First Aid on the first drive works
Did you repair any errors with First Aid?
The console shows no errors
Then the drive is not the likely issue unless you have possibly been disconnecting the drive by simply unplugging the USB cable.
Is that something you do?
First Aid on the first drive works, but I still cannot mount the other one. The console shows no errors. Does this mean the drive is the problem? If so, how can I recover my data?
Unable to access external hard drive
