Understanding Hard Disk Drives Media Defects
One of the most critical components of IBM Servers is the Storage Subsystem which includes
the RAID controller and the Hard Disk Drives (HDD). Typical HDD capacities found in today's
IBM Server Systems range from 2.25GB to 9.1 GB (1-Giga Byte 1 Billion bytes).
RAID 5 and RAID 1 architecture technology provides the ability to continue operation in the
event of HDD failures and provides the ability to rebuild lost data.
Although HDD reliability has greatly improved in the past five years, the areal densities
(defined below) have grown at a staggering 60% compound growth rate during that same time.
Due to the complexity of HDD's and the nature of the technology, media defects are a fact of life
in ALL HDD's manufactured today. However, HDD's employ effective error correction
techniques and data threshold analysis and reassignments to help prevent data loss. This manual
will explain the reason why media defects occur initially and why they may occur throughout the
life of the drive.
Topics included in this manual:
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