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Causes of data loss

Over the last 30 years, Kroll Ontrack engineers have restored a total of 103 million gigabytes. To store all that data, we would need about 25 million 4GB flash drives!

In this post, I want to share a few interesting figures with you. They all describe the mysterious world of data loss – usually quite similar to a horror movie. Fortunately in this world, most stories have a happy ending.

Let’s start with how many reported cases of data loss have a happy ending:

76% of cases of data loss end with partial or complete data recovery

In practice, it is possible to recover the data from most media storage types. Exceptions are extreme cases or when professional erasure methods are used. Sometimes, even if you manage to recover 98% of the disk, the data that the customer is after is located in those irreversibly lost 2%. In those cases – despite the best efforts, nothing can be done.

The best way to start describing the data loss is to group the most common causes of the data loss. As shown in the figure below, the most common type is hardware failure; interestingly the second most common reason is human error.

There isn’t much you can do to protect yourself from a hardware failure – except reading the instruction manual and use the manufacturer’s recommendations, of course. And in the case of a human error – well, usually it’s up to ourselves.


We’re usually only reminded about backups when something goes wrong. Of course, by then it’s too late and you’ll end up looking something like this…


People who have experienced a data loss can be divided into four categories:

  1. Those that used their backup to recover all data
  2. Those who have had a backup, but unfortunately it did not work
  3. Those who thought they had a backup, but the data on the backup was too old
  4. Those that did not have a backup at all

Perhaps the most surprising category is the second one but as a Kroll Ontrack survey shows, 65% of our lab clients had a backup in place. How is this possible?

In the case of an infrastructure failure often both the backup system and the main data storage fail simultaneously, preventing the recovery of the data. Another reason may be the fact that the backup does not have the most recent data because it was not updated by the system prior to the failure. Often it turns out that to restore the data from the backup is too expensive and/or time-consuming. For some companies, especially the big ones, any interruption in the operation might result in significant financial losses. This is when it is best to consider professional help.

Backup vs data archive

Another common mistake is the confusion between backup and the data archive. Both have similar methods of administration. Data archives and backups should be stored on a secure disk or server, independently from the system in which we use in everyday work. The similarities end here. The data we store in the archive is the data we don’t need every day but we want to/have to keep. Backups contain the copy of data, which is created in the event of failure of the original media, resulting in data loss. In addition to that, the archive itself should have its own backup.

In my next post, I will explain how data is written onto a disk, and what this means for the data recovery process. Until then!

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