Perpendicular recording has been actively developed for future high-density recording system. We studied the integration of the perpendicular recording system to the hard disk drive (HDD). Double layer perpendicular media and single-pole type perpendicular head with GMR reader were employed in 2.5" HDD. As a result of the integration test, it was confirmed that perpendicular recording 2.5" test HDDs functioned well at the capacity of 50 GB/platter. Through the drive integration, the features of the perpendicular recording were thoroughly studied. The complementary features between perpendicular recording and longitudinal recording are also discussed. (C) 2004 Elsevier B.V. All rights reserved.