Western Digital external hard drive is constantly ejected

I have a 1TB Western Digital external hard drive that I use for Time Machine backups, and recently my iMac has started to randomly eject the hard drive, preventing backups. It tends to happen while the display goes to sleep, but I have my Energy Saver settings set to not put the hard drives to sleep, and the computer is set to never go to sleep.

To correct the issue, I pull the USB cable on the drive and then re-attach it. I'm wondering if this is just a bad drive that I need to return or if this is some kind of larger issue.

Solution 1:

Someone reported a similar issue on an Apple discussion forum:

I tried that but the drive will still eject itself randomly at times.

I contacted Western Digital about this and they say it might be a problem with my USB cord. So they're going to send me a new one.

Has anyone else had this problem and found that it was due to a faulty USB 3.0 (compatible with USB 2.0) cord?

Another poster in the same thread commented:

Sounds like disk is on the way out. I would move or backup all data on it.

You should first back up that drive before anything else. Contact WD to see if they can send you a new USB cord. It's a good idea to run some diagnostics on the drive to confirm that there are no disk errors. Testing on another computer would also be a good idea to narrow down to see if the issue is isolated to your machine or the drive.

If the drive is failing, you'll need to return/exchange it.

Solution 2:

I had a similar problem with a 1TB 2.5" WD USB drive. It started to get randomly ejected while the MacBook was writing to it. Drive diagnostics didn't show any problems, reconnecting the drive didn't help. The simple solution was a reboot of the MacBook. (It hasn't been rebooted for about 2 months).