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Secure Erase (ATA)
Many hard drives and SSDs can erase themselves. The command for this is called Secure Erase and has been part of the ATA standard for years. It sounds simple – but in practice the result depends heavily on the drive. Here you can find out how the command works and where its limits lie.
In brief
Secure Erase is an erase command (SECURITY ERASE UNIT) built into the firmware of ATA and SATA drives, with which the drive erases its own user data. Unlike external software, the command works directly in the drive and can thus also reach areas that the operating system does not see. For IT decommissioning it is an important tool, but its effect must be verified and documented depending on the manufacturer.
How Secure Erase works
Secure Erase belongs to the "Security Feature Set" of the ATA standard. So that the function is not triggered by accident, a drive password must first be set. The SECURITY ERASE UNIT command then starts the erasure. The drive reports in advance how long the process is expected to take. After successful completion, the password is removed again.
The standard knows two variants:
| Variant | What happens (simplified) |
|---|---|
| Normal Secure Erase | Overwrites the normal user data area, on HDDs typically with zeros |
| Enhanced Secure Erase | Writes manufacturer-defined patterns to all user data areas, including no-longer-used, remapped sectors |
On SSDs, manufacturers implement the command differently. Some erase all flash blocks, others swap the internal key – this then corresponds to a Crypto Erase.
Limits and risks
- Implementation by manufacturer: What the command does exactly is determined by the firmware. From the outside, this can be verified only to a limited extent. Studies have shown that individual drives did not erase data completely.
- Locked drives: Many computers put drives into a "frozen" state at startup in which the command is blocked.
- Abort: If the process is interrupted, the drive may remain locked with the password set.
- Hidden areas: A Host Protected Area or a DCO area may remain untouched depending on the implementation if it is not removed beforehand.
- No proof: The command does not produce an erasure report. For audits, software that documents the result and serial number is needed.
Distinction from Sanitize and NVMe
Newer ATA drives additionally support the Sanitize command. It expressly covers all storage areas including caches and resumes the erasure after a power failure. NVMe SSDs use their own commands such as NVMe Format and NVMe Sanitize. Professional erasure software selects the appropriate method for each drive and verifies the result. An overview for HDDs and SSDs is provided by our guide Securely erasing hard drives and SSDs.
Relation to Second IT
Second IT erases HDDs, SSDs, and mobile devices with Blancco. The software also detects hidden areas such as HPA and DCO as well as remapped sectors and documents every erasure in a digitally signed erasure certificate with a serial number. Data carriers that cannot be erased securely are destroyed in-house in accordance with DIN 66399. More on the certified data deletion.
Frequently asked questions about Secure Erase
Is Secure Erase safe on SSDs?
That depends on the manufacturer's implementation. Many SSDs erase all blocks or swap the internal key with it. Because this is hard to verify from the outside, the result should be checked and documented for each drive.
What is the difference between Secure Erase and formatting?
When formatting, the operating system usually only creates a new file system, and the data often remains readable. Secure Erase is a command to the drive itself that erases the user data.
Why is the drive "frozen"?
Many computers lock the drive's security functions at startup so that malware cannot set a password. As long as this state is active, Secure Erase cannot be executed. Erasure software for professional use deliberately lifts the lock.
What is the difference between Secure Erase and Enhanced Secure Erase?
Both are ATA commands. Normal Secure Erase overwrites the normal user data area, Enhanced Secure Erase writes manufacturer-defined patterns to all user data areas, including remapped sectors. How thoroughly either works is determined by the manufacturer's firmware.
Does Secure Erase work on NVMe SSDs?
No. Secure Erase is an ATA command for SATA drives. NVMe SSDs use their own commands such as NVMe Format and NVMe Sanitize. Professional erasure software selects the appropriate method for each drive and verifies the result.
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