| 摘要 |
PROBLEM TO BE SOLVED: To attain shortening of a test time of a recording disk and high test reliability by more accurately predicting the number of defects on the basis of a test result about a portion of tracks in the recording disk. SOLUTION: An HDD 1 on one form of this invention performs the defect test of a magnetic disk 11. The HDD 1 predicts the number of defects at a stage where a portion of tracks is tested, and stops the test to thereby omit a useless test time when the predicted value exceeds a reference number. Each recording surface of the magnetic disk 11 is divided into a plurality of bands B0 to B8, and the HDD 1 selects each band at random and executes the test in the unit of the selected band. The total number of defects is predicted at a process where a test about a portion of bands is ended. By selecting the band at random, a more accurate predicted value is obtained and a testing speed can be accelerated. COPYRIGHT: (C)2007,JPO&INPIT
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