Help! I've plugged an external hard drive into my Mac and it's not showing up. What do I do?

Theoretically it should be easy to use an external hard drive with your Mac. Connect the hard drive to your USB or Thunderbolt port and the drive will appear in Finder.

But sometimes, even with Macs, things just don't work out. You connect the external hard drive to your Mac and nothing happens - the external drive has gone missing! Here's what to do.

See also:

Search for the missing hard drive

Before going any further, double-check the obvious stuff.

First, are you sure that the hard drive isn't showing up? Open a Finder window (File > New Finder Window) and scroll down to Devices. The hard drive should be here (underneath Remote Disc).

And check that the drive is properly plugged in, and hasn't wriggled its way out of the port. We've all been there, believe me.

Try to mount the hard drive in OS X Finder

Missing hard drive in OS X

Not made any basic errors? Of course not. Let's move on.

When you connect a hard drive to your Mac, it is connected but not necessarily mounted. Mounting a volume enables you to access its contents. (The reverse is also true: you can unmount a volume without ejecting the hard drive.)

Check to see if a hard drive is connected, but not mounted - and then mount a volume - by following these steps:

  1. Open Disk Utility (choose Go > Utilities to find it).
  2. Check to see if you can find the hard drive in the list on the left.
  3. If you can see the hard drive, check underneath it for a volume. (If it is present it will be greyed out.)
  4. Highlight the volume and click the Mount icon.

Now open a Finder window and check under Devices to see the mounted hard drive.

Missing hard drive? Try more power

Missing hard drive Y cable adaptor

If you connect a USB hard drive and it doesn't show up in the Finder, the chances are that it needs more power. USB carries power to the drive, but some drives need more than the 5V that comes through a single USB port.

Some USB cables split into two USB connections for your Mac and lead to the single USB connection on the hard drive. This is known as a USB power cable. This provides more power for the hard drive, and enables it to work directly from your Mac. You can pick one up for around £5.

If you don't have a dual USB cable, you can try connecting a separate power supply if one came with the external hard drive. This will provide ample power to drive the external hard drive.