Find out how data gets corrupted and how it can be recovered

23 June 2017 by Michael Nuncic

Have you ever tried opening a digital photo or a file inside an application, only to be prompted that it could not be opened due to corruption? You are not alone. Data corruption is far more common than one might think and has been an issue ever since the beginning of the computer era. Data corruption, in simple terms, is used to describe when the data inside a file has been changed from its original state.

However, it is entirely subjective if data or file corruption should be considered as a serious matter. If you cannot open a private text document or you have been left with a partial photo, it might not be worth mentioning. But if you work in a company, which can have thousands of files rendered unusable, then it could certainly be considered as a business-critical issue. Therefore it is very important to immediately check your whole system after a corruption incident has occurred, to determine the reasons for the corruption and to solve the problem as fast as possible to prevent further damage.

Why do files get corrupted?

There are various causes of data or file corruption and in many cases; files can become corrupted when storage devices get old.  Several studies about the lifespan of traditional hard disks show that the failure rates in the last two years of the disk increases to its peak. The result of these ‘normal’ wear-out related failures can be that during operation (or even when the disk is not in use) the data stored is changed from its original form. Files then get corrupted and cannot be used anymore. If this happens to pictures, the result can often look like the image above!

Another likely reason for corruption can be a power surge or a sudden loss of power. When files are being saved onto the hard disk drive and an unexpected power outage takes place, only parts of a file may be transferred correctly, leaving the entire file corrupt.

This also happens to SSDs; when the controller in an SSD stops working or is not communicating with the storage chips correctly, the result is the same as if the power went down and any files being transferred can become corrupted. Even if the corruption is not that serious and the file can still be opened, this doesn’t mean that all of the content is still correct. For example, one possible and dangerous result is when an Excel sheet or a database is missing important figures and in the end the whole calculation turns out to be false.

Is it possible to recover corrupted data?

Think of two common types of files which could be corrupt: a Word (.docx) file and an image file like a .jpg or a .png file. In both cases when you try and open it you may get a prompt that the file is corrupt and cannot be read. But what are you supposed to do now?

To keep it simple, there are two different ways to retrieve corrupted data: using a data recovery software tool and getting help from a professional data recovery service provider.

In some cases the damage is not that severe and data recovery software can successfully find fragmented parts of the file on other sectors of the disk and rebuild it.

Be warned, though, as DIY data recovery is always a risky business. Using data recovery software (as well as trying other DIY methods) can be hazardous when used incorrectly. As a rule, these tools shouldn’t be used on the original drive – instead they should be used with an image or copy of the drive. By doing so, there is still a chance for data recovery experts to forge a successful recovery if DIY attempts fail. What’s more, it prevents more damage to the drive and eliminates the chance of destroying the files for good. Files recovered with software tools should also not be written back to the original volume until they have been fully tested and verified.

Expert data recovery engineers can do far more than even the best software can do. If there is an underlying hardware issue, they often can repair the damage and recover the underlying data or can repair the drive to the point where they can fill in the missing or corrupted data. It is also possible for specialists to use data from spare blocks or parity to correct other types of logical damage and rebuild corrupted files. All of these measures are not possible for an average user due to the experience, knowledge and specialist tools required to determine if a corrupted file is recoverable or not.

Minimising the risk of further data loss or damage

So, what can you do to get back corrupted files without causing further damage? First, don´t panic! Try to stay calm and carefully evaluate your options. When dealing with data corruption it is wise to follow a plan that includes the following steps:

  • Make a sector level image of the drive that contains the corrupted file(s). There are a lot of free tools on the market that do this. As mentioned before; only attempt DIY recovery on the image and not the original drive! Set the original drive aside in case things don’t go well during your attempts to recover the data - it can be used later on by data recovery experts if needed.
  • After you have successfully recovered your corrupted data, you can try and use a reputable file repair tool. There are lots of products available on the market, so make sure that you choose a well-known, quality product for your specific use case. These types of tools work best for office documents, however there are still some tools available for databases, videos or photos which may be able to help.
  • Don´t use the built-in OS volume repair tools to fix the disk (like CHKDSK or FSCK). Using built-in tools will often cause more damage and prevent the data from being recoverable.
  • If none of these steps work and you still need the data, contact an IT professional or an experienced data recovery service provider for further advice.

In many cases data recovery specialists are able to retrieve data using highly specialised tools, which greatly surpass any DIY method. If your data is important then it’s worth trusting it with a professional rather than attempting a recovery yourself. If you’re in doubt, get in touch with a reputable data recovery company, like Ontrack, as you’ll be able to get some advice on the best course of action based on your exact data loss scenario.

Have you ever lost data due to corruption? Were you able to get your data back? Let us know by tweeting @OntrackUKIE