How to Fix: Device I/O Error (and Recover Data)

Dennis Faas's picture

Infopackets Reader Phoebe A. writes:

" Dear Dennis,

Today I tried to free up some space on my C drive by moving files over to my external hard drive, but Windows gave me an error message, stating that 'Error during copy: the request could not be performed because of an I/O device error'. I've also tried using 'TeraCopy' to copy files over, but it keeps freezing on the same files. Can you help? "

My response:

If you receive an error that says "the request could not be performed because of an I/O device error" when trying to copy or move a file, that usually (but not always) indicates bad sectors on the drive. In this case I asked Phoebe to connect to her system using my remote desktop support service to have a closer look, and she agreed.

How to Fix: Device I/O Error (and Recover Data)

The first thing I did was open an administrative command prompt and run a 'check disk' (or chkdsk) in order to check for file system errors. If a PC has file system errors, this can cause all sorts of strange phenomenon - including I/O device errors. Thankfully, there were no file system errors reported.

Next, I ran 'sfc /scannow', which is the Windows "system file checker". The purpose of this program is to check Windows system files on the hard drive for corruption. SFC errors can cause all sorts of issues, including spontaneous blue screens of death (BSOD), programs failing to run, strange error messages, and the like. If her system reported SFC errors, I knew that any further testing may not be possible (or reliable) because this essentially means the operating system is corrupt. Thankfully, the 'sfc /scannow' command reported "no integrity violations".

With chkdsk and 'sfc /scannow' out of the way, the next option was to run Macrorit Disk Scanner (freeware) to run a surface scan of the hard drive. This tests the system for bad sectors. As I mentioned previously, bad sectors on the drive are almost always the cause of a device I/O error. A surface scan can take hours to complete - usually anywhere from 2 to 4 hours or more. I let the program run and checked back in a few hours, and found one bad sector on the drive. I knew this was the reason she was experiencing a "device I/O error".

Recovering Data from Bad Sectors

The next step was to safely copy the data from Phoebe's C drive onto her external drive.

Unfortunately, being able to copy the data is easier said then done, especially when you are facing "device I/O errors". That's because most programs will simply abort if they encounter and I/O error - just as the Windows file copy did. The same is true when using Acronis True Image or Macrium Reflect to create a full disk image of the system.

For the record, disk images - when possible - are the preferred backup method as they collect the entire drive's data, plus they can be converted into virtual machines (most of the time but not always). Virtual machines are incredibly useful for exporting data from programs on a previously corrupted system (if that is an option). However, since we are dealing with I/O errors, a disk image simply is not possible. As such, I needed a different kind of tool to recover Phoebe's data - one that could handle "device I/O" errors and keep on chugging.

Enter: "Roadkil's Unstoppable Copier". This program can be used to copy the contents of the entire hard drive (or part of it) - even if it has bad sectors, though full data recovery isn't guaranteed. The best part about this program is that it won't freeze when it encounters a bad sector like other programs do. This is extremely useful! You can even set how the program handles problematic data due to bad sectors: whether to try recover the data, or to simply skip the file. When the copy is complete, Roadkil's Unstoppable Copier reports which files it couldn't copy, though this isn't easily viewable if you use "batch mode".

After using Roadkil's Unstoppable Copier, I downloaded and installed "pathsync" to compare the contents of the directories I copied from Phoebe's C drive with the external drive. The purpose of this program is to sync paths (folders); it also reports to the user which files are missing on the target (in this case, the external drive). As such, I was able to figure out which files were not copied using Roadkil's Unstoppable Copier due to bad sectors.

Replacing the Dying Hard Drive

After recovering all of Phoebe's important data, I recommended she buy a new hard drive to replace the one with bad sectors.

There are some people who may instead recommend using a program like "spinrite" to get around bad sectors, but I wholeheartedly disagree with this approach. The fact is: if a disk has bad sectors, it is because it already has used up all its unallocated "free slots" for bad sectors, which means it's in the process of failing. If you continue to use the disk, it will likely continue to develop bad sectors - similar to how cancer spreads in the human body. And with the price of hard drives being relatively cheap these days, there is absolutely no point in holding on to old technology that is much slower than it needs to be - and one which is failing.

In Phoebe's case, her old hard drive was benchmarked at 80 megabytes per second which is very slow for today's standards. The hard drive I recommended for her was an SSD (solid state drive) which is MUCH faster and has no spinning platters and does anywhere from 250mb/sec to 500mb/sec in transfer speeds. All said and done, the SSD doubled the speed of her computer - plus it got rid of the I/O error.

At this point she reinstalled Windows 10 on her system and I recovered her data back onto the SSD. Problem solved!

Additional 1-on-1 Support: From Dennis

If all of this is over your head, and if you are encountering "the request could not be performed because of an I/O device error" error message and need help resolving the issue - I can help using my remote desktop support service. Simply contact me and briefly describe the problem, and I'll get back to you as soon as possible.

Got a Computer Question or Problem? Ask Dennis!

I need more computer questions. If you have a computer question -- or even a computer problem that needs fixing - please email me with your question so that I can write more articles like this one. I can't promise I'll respond to all the messages I receive (depending on the volume), but I'll do my best.

About the author: Dennis Faas is the owner and operator of With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.

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kitekrazy's picture

I rarely go that far with disk problems but thanks for the list of utilities.