| 摘要 |
An HDD has a raised portion including a substantially circular pattern. The pattern includes first to third arcuate stepped portions. The first stepped portion opposes the outer periphery of the disc. The second stepped portion is located inside the first stepped portion and closer to a disc than the first stepped portion. The second stepped portion is included in the second stepped portion and located closer to the disc than the second stepped portion. The first to third stepped patterns extend through a certain angle in a position deviated from the movement route of a magnetic head over the disc.
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