Disk Space Guide

• Size units
• Cluster size and slack
• NTFS-specific features
• Disk space visualization software
• Automated disk cleanup software
• Disk space usage in RAID
• Host Protected Area (HPA)

Host Protected Area (HPA)

Host Protected Area (HPA) - a disk area which is invisible to an operating system. With HPA it is possible to have an indicated disk capacity less than "real" physical capacity. HPA feature is used for:

• compatibility with older motherboards which cannot see disks larger than 128/137 GB.
• storing the factory copies of Windows (typically in laptops) instead of Recovery CD.

HPA is managed by special software, for example HDD Capacity Restore tool which is capable of removing the configured HPA limitation.

Sometimes HPA can activate spontaneously. In this case your disk size decreases producing one of the forms of the phenomenon called capacity clipping.