My 1 TB Hard Drive is only sometimes usable.

[theantidavis]

As the title suggests, my 1 tb hard drive has become a problem recently. Around 30% it works flawlessly; most of the time, however, it is visible in device manager as an unknown device under "disk drives". When it's in this state, if I go into disk management and try to partition it, it claims that there is an I/O device error. I can't seem to find a solution online; please help!

 

[SuperSoph_WD]

Hey there, theantidavis!

Your issues with the hard drive seem quite devastating. 🙁 Unfortunately, the I/O error could be indicating failure of the HDD. However, the best way to determine what is the heath and SMART status of that drive would be to test it using the manufacturer's diagnostic tool. You should be able to find this utility somewhere on their website.
In case you cannot, you can refer to this thread from the community with some pretty good third-party suggestions as well: http://www.tomshardware.co.uk/forum/282651-32-best-diagnostic-testing-utility

I'd strongly recommend you to back up any data that you can access from the HDD before proceeding with the troubleshooting. I'd also suggest you to re-seat the SATA/power cables to the drive.

Keep me posted with the SMART results! Good luck!
SuperSoph_WD