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Host Protected Area (HPA)
In brief
The Host Protected Area (HPA) is an area at the end of an ATA or SATA hard drive that is hidden from the operating system by the drive reporting a smaller capacity. Manufacturers use it, for example, for recovery or diagnostic data. In IT decommissioning the HPA matters because erasure programs that do not detect it cannot reach the data stored there.
How does an HPA arise?
The HPA was added to the ATA standard in the late 1990s. Using a command, software can reduce the maximum addressable capacity of the drive. The rest continues to exist but is invisible to the operating system and normal programs. A similar mechanism is the Device Configuration Overlay (DCO), with which the reported capacity and individual functions of a drive can be changed.
| Feature | HPA | DCO |
|---|---|---|
| Purpose | Protected area, e.g. for recovery | Adjusting capacity and functions |
| Visible to the operating system | No | No |
| Risk during erasure | Remains untouched by simple software | Remains untouched by simple software |
Significance for data erasure
An HPA can also be set up deliberately to hide data. For a complete erasure, the software must detect HPA and DCO, temporarily remove them and process the entire data carrier. The erasure report should record whether hidden areas were found. Second IT erases with Blancco. Hidden areas such as HPA and DCO as well as redirected sectors are detected, displayed and erased. More on certified data deletion.
Frequently asked questions about the Host Protected Area
How do I find out whether a hard drive has an HPA?
Special diagnostic and erasure programs compare the reported with the actual capacity. If the two differ, an HPA or DCO area has been set up.
Is there an HPA on SSDs too?
Yes, SATA SSDs can also have an HPA. With SSDs, reserve areas managed by the controller are added as well. These require their own erasure methods.
Does formatting remove the HPA?
No. Formatting only works in the visible area of the drive. The HPA remains with its contents.
What is the difference between HPA and DCO?
Both are invisible to the operating system. The HPA is a protected area, for example for recovery data. The Device Configuration Overlay (DCO) adjusts the capacity and functions of a drive. Simple erasure software leaves both untouched.
Why is the HPA a problem for data erasure?
Erasure programs that do not detect the HPA do not reach the data stored there. The software must detect HPA and DCO, temporarily remove them and process the entire data carrier. The erasure report should record whether hidden areas were found.
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