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Datenremanenz
In brief
Data remanence refers to residual data that remains on a storage medium after data has apparently been deleted. It arises because deleting, formatting or resetting often removes only references, not the data itself. In IT decommissioning, data remanence is the core risk against which certified erasure methods and the destruction of data carriers protect.
How residual data arises
- Deleting in the file system: The operating system only marks the space as free. The contents remain until they are overwritten.
- Formatting: A Quick format only creates a new file system.
- Hidden areas: Hard drives can hide areas such as the Host Protected Area; reallocated sectors can no longer be reached from the outside.
- Flash memory: SSDs write changed data to new locations and keep spare blocks in reserve. Old versions can remain behind.
- Main memory: RAM too can still partly retain its content for a short time after being switched off. For decommissioning this hardly matters, but for the security of running devices it does.
What helps against data remanence
Effective are methods that cover all memory areas and whose result is verified: Overwriting for hard drives, firmware commands or Crypto Erase for SSDs and physical destruction for defective data carriers. The umbrella term for this is explained in the entry Data Sanitization. Which methods suit which drive is shown in our guide Securely erasing hard drives and SSDs.
Second IT erases with Blancco, including hidden areas such as HPA and DCO, and creates a digitally signed erasure certificate for each device. Data carriers that cannot be erased are destroyed in-house in accordance with DIN 66399.
Frequently asked questions about data remanence
What does data remanence mean?
It is residual data that remains on a data carrier after an attempt to delete it and that can possibly be recovered.
Does a factory reset remove all data?
Not reliably. Depending on the device, data remains in free or hidden areas. For companies, proof for each device is also missing.
How do I prove that no data has remained?
Through an erasure certificate for each serial number that documents method, result and verification, or through a certificate of destruction.
Can data be recovered after formatting?
Often yes. A quick format only creates a new file system; the old contents remain on the data carrier until they are overwritten. Secure erasure requires methods that cover all memory areas.
How do I prevent data remanence on SSDs?
With the drive’s firmware commands or with Crypto Erase. This is necessary because SSDs write changed data to new locations and keep spare blocks in reserve. Old versions can remain behind there. Defective SSDs are physically destroyed.
No residual data: erased with certification, with proof for each device.
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