How To Fix I/O Device Errors On External Hard Drives

Fixing I/O device errors on external hard drives can be simple, difficult, or impossible depending on your situation. The good news is that you can often diagnose the problem with a few quick tricks and some equipment you already have at home.

The Problem With I/O Errors

The problem with Input/Output (I/O) errors is that they’re generic—the error messages you see are what Windows, Mac, and Linux say when they know there’s a problem but they don’t know exactly what that problem is.
It could be that your USB or eSATA cord is a little bit loose. Or it could be that your external hard drive is knocking on death’s door. That means you’re going to have to do some sleuthing—you can’t just find a blog by somebody who got the same error message and do what he did.

The Easiest Problems To Fix

Some I/O errors are really easy to fix. Most them have to do with the cords that connect your external hard drive to your computer.
The first thing to check—and you may already have done this—is that all of your cords are connected tightly. Check the connection to your external hard drive and to your computer. If you’re connecting to a USB hub, make sure the cord from the computer to the hub is connected tightly at both the hub and computer ends or—and this is preferred—connect the external hard drive directly to one of the USB ports on your computer, bypassing the hub and any problems it may have.
The next easiest problem to fix is cord crosstalk. The electricity in one set of wires tends to leak into other wires, so when you have two wires close together on your desk, they may be interfering with each other. Interference isn’t a big deal to your mouse or keyboard—Windows just ignores spurious data—but it’s a big deal to your hard drive where Windows assumes the files it opens and saves are accurate.
To check for crosstalk problems, disconnect any unnecessary devices on your computer and move the cords for the necessary devices further away from your external hard drive. You may also want to disable Bluetooth and move your cell phone across the room.
Don’t worry, if you have a crosstalk problem, you can avoid I/O device errors on external hard drives permanently by buying better cables—just look for shielded cables. Good shielded USB cables include dampeners on both ends: these are little cylinders containing magnets near the plugs.
The final cord-related problem requires a friend or an expenditure. It could be that you have a faulty cable. This is especially likely if you just bought your external hard drive or if you tend to abuse your cables by not putting them away properly.
If you have a friend with a similar external hard drive (and the cables aren’t hardwired), borrow his cables. If that’s not an option, buy replacement cables. You should be able to buy short replacement cables for USB and eSATA for less than $5 if you shop around.

Difficult But Fixable Problems

If you don’t have a cord problem, the chances that you’ll be able to recover from I/O errors decreases rapidly. Since there are two types of hard drives, there are two different sets of solutions.
For magnetic (high capacity) hard drives, I/O errors often start occurring when the ball bearings get worn or bent out of shape. This happens mainly to drives which have been active for more than two years total or drives which have been dropped. If you get I/O errors on a new external hard drive, I recommend you return it immediately—it was probably dropped during shipping or part of a defective lot.
A key sign that your I/O problem is caused by bad ball bearings is clicking or grinding noises inside your external hard drive every time you plug it into your computer.
You can often get a magnetic drive to start working again by shrinking the ball bearings a little bit so they fit back into their regular tracks. How do you shrink an almost microscopic ball bearing inside a hermetically-sealed hard drive? Basic physics: you freeze it—all metals shrink when cooled.
Note that this can be dangerous and there’s a risk that not just your data and your computer will be destroyed but that you’ll be electrically shocked.
Put your magnetic external hard drive in a Zip-Lock bag. Squeeze out the air. Then put that bag inside another Zip-Lock bag and squeeze out that air. Put a rubber band around the drive in the bag to keep new air from leaking in so you don’t give your hard drive freezer burn.
Put the bagged external hard drive in the freezer for at least an hour and preferably overnight. Then get your computer ready to copy files off the drive as fast as possible.
When you’re ready, take the hard drive out of the bag, connect it to your computer, and start copying files. If the hard drive dies in the middle of copying, freeze it again. Hopefully with this technique you can recover all of your important files. Here are some detailed instructions  on how system administrators recover data.

Solid State Drive Recovery

Solid state drives tend to fail more gracefully than magnetic drives, so you don’t need to explain to your family why you have a hard drive in the freezer.
The main cause of I/O errors on a solid state drive is too many writes. Every time you save a file to a solid state drive, you use up one of the limited rewritable sectors. Early solid state drives had about 10,000 writes; modern drives typically have 100,000 to 1,000,000 writes.
Once the writes are gone, you can no longer write to that sector. You can still write to other sectors, but Windows isn’t smart enough to only write to working sectors, so it gives you the I/O error.
There are two pieces of good news here—one short-term and one long-term. Short-term, you can still copy files off of your solid state external hard drive, so you haven’t lost any data. Long-term, researchers are working on new tools which will allow computers to work around failed solid state sectors so you can start to write files again. But until then, there’s no real way for solid state drives to fix I/O device errors on external hard drives.