Remember the HPA and DCO When Sanitizing Hard Drives

Forgetting Something? Remember the HPA and DCO When Sanitizing Hard Drives

So you’ve performed a hard drive wipe, hoping to make sure that any and all data on your hard drive is completely gone. And when you check your hard drive’s specs, it certainly appears to be empty. But are you really done? Maybe not.

Many modern hard drives support the creation of hidden storage areas that are not accessible through standard means.  Typically, the BIOS and operating system of a PC aren’t aware of these areas; and, in many cases, neither are users.

The HPA (Host Protected Area) can be set aside as a storage area that can potentially go undetected. For example, an HDD that can actually hold 250GB of data can appear to hold only 245GB of data – the extra “hidden” 5GB of storage space can then be used to store applications, utilities, or data that will only be accessed by certain software or firmware. This area is often used to store backups of system files which can be copied back to the boot partition when restoration is needed.

DCO (Device Configuration Overlay) works in a similar fashion as the HPA. It was originally created so that hard drive and PC manufacturers could create identical storage capacity specifications while using hard drives of differing physical capacities. Unlike the HPA, a DCO can only be removed under certain conditions; for example, any existing HPA must be removed in order to restore a hard drive.

While it would be very rare for sensitive information to accidentally end up in either of these hidden areas, data could, in fact, be intentionally stored in these little-known-about storage spaces. You may, in fact, not be completely sanitizing/wiping your hard drives if you don’t use the specialized tools that are equipped to handle these areas.

Aleratec’s hard drive duplicator and sanitizer towers – with the latest firmware – have hard drive sanitization features that remove any HPA and DCO areas before overwriting the drives, ensuring that they are fully sanitized. This feature is available on each of the three overwrite options: one-pass, 3-pass with verify and 7-pass 5220.22-M.  Be sure to check them out on our website at

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