Mac – External drive not detected on MBP until it’s connected to a Windows machine first

external-diskhard drivetime-machine

I have a WD "MY Passport" 1 TB drive which I use for my TimeMachine backup on a 15" MacBook Pro (Mid 2014).

Sometimes, the mac will not detect when the drive is being connected (it's not showing in the disk utility either). Rebooting the mac does not help.

However, after some experimentations, I found out that if I connect the drive to a Windows machine, disconnect it and then connect it to the mac, it's detected and can be used with no issues (until the next time it's not detected).

This happened to me on another drive (a seagate drive) as well.

Anyone has any idea what's going on here?

Best Answer

You do not have the "standard" formatting on the WD: for TimeMachine it should be imperatively GUID Partition Table. and. Mac OS X Extended (journaled). If it really has that, open DiskUtility and select the WD, then select the FirstAid tab: it will check and repair permissions.

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