If your external drive is being a bit temperamental, there are a few things you can try before taking a hammer to it in frustration or sending it in for repair. Give these a go and see if they help:
1. Plug it in. Low power can impact performance, so where possible you should plug your drive in to the mains rather than relying on bus power.
2. Switch ports and cables. We know it’s an obvious one, but if there are multiple ports you can connect your drive to, try them all to make sure it is the drive that’s the problem and not the port itself. If your drive’s connecting to a USB hub or similar device, try connecting it directly to your computer instead. If you’re working on a desktop computer, use a port on the back of your computer rather than on the keyboard. If you have any additional FireWire, USB or Thunderbolt cables, try using those, too.
3. Relaunch Finder. Sometimes a drive can be available and working fine, but Finder fails to display it properly. To turn Finder off an on again, hold down the alt key, right click on the Finder icon in your dock and click Relaunch in the popup menu.
4. Check your formatting. It may be that your drive is formatted using a file system your Mac doesn’t understand. You can check this by opening Disk Utility (click Go in the top menu, click Utilities and select Disk Utility) and checking the Format field in the bottom left of your screen. It should read Mac OS Extended (Journaled) or MS-DOS (FAT32). If it’s not in a supported format, you’ll need to reformat the drive before your Mac can access it, but this will wipe any information on the drive, so make sure it’s backed up first.
5. While you’re in Disk Utility… If your Mac can definitely see the drive but you can’t access content on it, open Disk Utility and click on Verify Disk. Your Mac will scan the disk to see if it can pick up any errors. If it does find errors, click on the Repair Disk button to troubleshoot them. (You can see our video on the wonders of Disk Utility here.
6. Boot in Safe Mode. It may be that third party plug-ins or something else installed on your computer is causing problems with the drive. You can check for this by booting in Safe Mode (power off your Mac and reboot it while holding the Alt key down until the grey Apple symbol appears). This mode only enables the core functions of your Mac, so if your drive is recognised in Safe Mode the problem probably lies with a third-party program installed on your computer.