Hardware Reference
In-Depth Information
Originally, this was done using a hidden partition, which unfortunately could easily be
damagedoroverwrittenbypartitioningsoftwareorotherutilities.Inmanynewersystems,
the contents of the recovery disks are instead preinstalled in the HPA, which is accessible
via Protected Area Run Time Interface Extension Services (PARTIES), a standard sup-
ported on all ATA-4 or newer drives. HPA/PARTIES works by using the ATA
SET MAX
ADDRESS
command to essentially make the drive appear to the system as a slightly smaller
drive. Most manufacturers use the last 3GB of the drive for the HPA. Anything from the
new max address (the newly reported end of the drive) to the true end of the drive is con-
sidered the HPA and is accessible only using PARTIES commands.
Figure 5.9
shows the
contents of the HPA and the relationship between the HPA and the rest of the drive.
Figure 5.9
The Host Protected Area (HPA).
The HPA is more secure than a hidden partition because any data past the end of the drive
simply cannot be seen by a normal application, or even a partitioning utility such as Par-
tition Magic or Partition Commander. This makes it far more secure and immune to dam-