Understanding corrupt data
Have you ever seen a corrupted digital picture or you were unable to open a file inside an application due to data corruption? You are not alone. Data corruption is far more common than one might think. Since the beginning of the computer era, users have faced the problem of data corruption. When your data is corrupted, in simple words, means that the code of a file or inside data has been changed from its original state.
However, it depends on the user’s assessment if data or file corruption is a serious matter or not. If you cannot use non-critical files like a holiday letter from 1993, it might not be worth mentioning. However, if you work in a company, which has thousands of files that are not usable anymore, then it might be a business-critical issue. Therefore, it is very important to immediately check for damage after a corruption incident has occurred. Questions one might ask right away are: why did the file become corrupt and how fast can it be fixed?
The reasons for data corruption
There are various causes for data or file corruption. In many cases, files can become corrupted when the storage device gets old. Traditional hard disk drives (HDDs) lose their magnetic orientation or their magnetic fields weaken. The result is that during operation, or even when the disk is not in use, the stored data is altered from its original form. Files then become corrupted and can no longer be used. If this happens to a picture file, it can often look like the picture above. Another likely reason for corruption can be a sudden loss of power. When files are saved onto the hard disk drive or a chip-based SSD and an unexpected power-outage takes place, only parts of a file are transferred correctly, causing the entire file to be corrupt. This also happens to SSDs. When the controller in a SSD stops working or is not communicating properly with the storage chips, the result is the same as if there was a sudden loss of power; files that are in the transfer process will experience corruption. Even if the corruption is not that serious and opening the file is still possible, this doesn’t mean that the content is still valid. One possible and dangerous result of this 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 data recoverable after corruption?
Think of two common types of files which could be corrupt: a Microsoft Word document and an image file like a .jpg or a .png. In both cases, the user gets a message from their software application that the file is corrupt and unreadable. While it is possible to recover these files, the guarantee to fully restore all original files is not 100%.
Data recovery software and experts take parts of a corrupted word document and can then copy it into a new word document. Some content from the document will be unrecoverable, but at least major parts are readable and usable like before.
Data corruption for images
When it comes to images, the damage is often more severe. Even when only parts of an image show impact, it lasts forever. Only the upper 20 % of an image is visible. The rest is corrupted. Unfortunately, no data recovery expert can do anything about that. When a video file is corrupt, one might have luck. Often “only” the index of an .avi or .mpg file shows damage and several tools can fix this problem to salvage the video.
It is important that users are aware of what is typically recoverable from file corruption. The same goes for databases, excel or pdf files. Only parts of the files are recoverable and some content is unrecoverable.
If a database experiences corruption, it is better to recover and rebuild as much of the files as possible and fix the files in order to keep the system running.
Tips to minimize the effects of data corruption
Tip 1: Don’t panic
Try to stay calm and carefully evaluate your options. In the case of file corruption, it is wise to act according to plan. It includes the following steps:
- Try to get the file running again by trying to fix the problem. Use the build-in OS error tools to fix the disk and after successfully doing that, try to open it again.
- Use a data recovery tool. In some cases, using a software tool will be able to fix a corrupted file.
- If you have a backup ready, use it and forget about the above steps. It is the fastest way to get a hold of the file again. Maybe you have to make changes to the file manually, but in many cases, this takes far less time than to recover a corrupted file.
- If none of these steps work and you still need the content, contact an experienced data recovery service provider.
Tip 2: Check the health of your storage disks and devices frequently
Even if you are just a lazy private computer user, make sure you are always checking the health of your hard disk drive. It is the only way to protect against data loss caused by corruption. As we have pointed out before, data corruption can be a cause of normal material degeneration of the build-in platter or its surface. Since in many cases, a data recovery is not possible, it is necessary to take precautions by checking the disk (HDD and SSD). To check the health and future lifetime of a disk, you can use one of these S.M.A.R.T. diagnostics tools available on the market like HDtune, HDDScan or CrystalDisk Info. Even though they are free, they offer a lot. All of these tools perform disk health tests and offer the status of their current health level. Additionally, some tools also predict the time period remaining for disk use or the estimated disk degradation, so the user can back up their data before it is too late.
Tip 3: In the case of a HDD, use the defragmentation tool as often as possible
When parts of a file are on several different individual blocks, it is almost impossible for any data recovery tool to find out which part of a file in a certain block belongs to another part on another block. The chances that the data recovery software will repair usable files are much better when using the defragmentation tool, so the parts of a file will most likely be in chronological order.
Tip 4: It is always a good idea (and best practice) to have a current external backup of both your data as well as all the necessary application and system files available. With this at hand, data corruption might not be a severe matter.
Read also: How to Handle a Corrupted Hard Drive
4 steps to reduce the impact of corrupted data
- Don’t panic
- Check the health of your storage disks and devices frequently
- In the case of a HDD, use the defragmentation tool as often as possible
- Have a current external backup of both your data as well as all the necessary application and system files available
In most cases, data is gone forever and there is no way of getting back the valuable information. However, in some cases, data recovery specialists use highly specialized tools and knowledge to retrieve at least some of the data.
If it is imperative to recover lost data, you should get in contact with a professional data recovery service provider like Ontrack. They will inform you within a short period of time if the data is recoverable or not.
Picture copyright: Ontrack GmbH using MOSH
Michael Nuncic is Marketing Communications Manager at the German Ontrack Data Recovery office in Böblingen for more than 5 years. Highly experienced in computer, network and software topics, he is a professional editor for blog and technical articles for almost 20 years now.