Unmountable drives

[nelly22]

I have few external USB 3 Hard Drives 2 - 5 TB which don't mount.

I have tried different power sources, USB-cables and USB-ports.

Disk Utility don't see but System Information, lsusb and ls sees drives.

All drives turn led on and some spins plates but some not.

Is there any app or unix thing which can mount these or can copy data out?

MBPR 10.13.5.

 

[hobowankenobi]

Do you know how they were formatted? Do they behave connected to a Mac on 10.12 or older? What else can you tell us about them?

 

[techwarrior]

If they are a format macOS doesn't recognize like Linux ext*, they won't mount.

If they previously mounted but you had a power outage or some other event that caused them to disconnect without unmounting, the OS gets confused. Shut down the Mac, pull all power or do a NVRAM\PRAM reset (OPT + CMD + P + R).