Is It Possible to Recover Overwritten Data?

Nowadays, data loss is very common. At the same time, data recovery also becomes increasingly developed. Many users are confused about whether it is also possible to recover overwritten data. This article will delve into this issue.

In the current fast-evolving digital era, data is all-pervasive. Also, data loss is one of the most common occurrences for both individuals and businesses. Without any doubts, no one is willing to accept such terrible events. Generally, in the event of data loss, the next step is definitely data recovery, such as PST recovery.

Is It Possible to Recover Overwritten Data

Fortunately, with data recovery technologies constantly developing, most of time, it is possible to recover data. But, is it also possible to restore overwritten data? In the followings, we’ll focus on this issue, take hard drive as an example and proceed to discuss it in detail.

How Data Is Stored on Hard Drive

In the first place, you should learn a bit about how hard drive stores data. Put simply, data is saved non-volatile and magnetically on hard drive. In this way, maintaining the saved data won’t demand power supply. Every magnet has plus and minus pole which represents the binary code. The hard drive platter has a ferromagnetic surface, which is divided into small magnetic domains. Hard drive utilizes directional magnetization on these domains to restore data.

Hard drive stores data in two approaches. The first one is on the magnetic drive physically. And the second one is logically file system management. The latter one will create data table which indicates the exact physical location of the data.

What Happens when Data Gets Inaccessible

To be honest, data can become lost or corrupt due to various factors. Here we’ll look at two data loss cases. One is deletion. The other one is accidental disk formatting.

  1. Mistaken Deletion: In general, when you delete any data on hard drive, say a word document, the data stored in the file system’s table is removed. But its physical location on the magnetic hard drive remains untouched. So, it is still possible to recover the deleted file.
  2. Disk Formatting: The formatting performed by users is usually to empty the file system on the hard drive. Therefore, similar to mistaken deletion, after formatting disk, only the data in file system is cleared. You still can get back it from the drive physical magnetic domains.

What Happens when Data Is Overwritten

However, unlike the above two scenarios, when data is overwritten, the relevant HDD magnetic domains will be re-magnetized. In other words, it will physically eliminate the data on the location where the overwritten data is stored. Now that both the data on file system table and the data on the physical drive are cleaned up, few residual physical changes traces can be left behind. Thus, it is certain that recovering the overwritten data is impossible.

Author Introduction:

Shirley Zhang is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including mdf recovery and outlook repair software products. For more information visit

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