Method of controlling rotation of optical recording medium at two or more rotational speeds, and storage apparatus employing same method

A storage apparatus having a spindle motor which rotates an optical recording medium at two or more kinds of rotational speeds, comprising:

• a controller configured to decrease the rotational speed when a read or write margin becomes less than or equal to a first predetermined value, and increase the rotational speed when the read or write margin becomes greater than or equal to a second predetermined value or, when the frequency of generation of the servo abnormality of the tracking servo and/or the focus servo is less than or equal to a second predetermined frequency, said read or write margin being based on an error rate obtained as a result of a test write and a read without error correction.

A storage apparatus having a spindle motor which rotates an optical recording medium at two or more kinds of rotational speeds, comprising:

• a controller configured to decrease the rotational speed when a read or write margin becomes less than or equal to a first predetermined value, and increase the rotational speed when the read or write margin becomes greater than or equal to a second predetermined value or, when the frequency of generation of the servo abnormality of a tracking servo and/or a focus servo is less than or equal to a second predetermined frequency,
• wherein said controller is configured to also decrease the rotational speed when the frequency of generation of the servo abnormality of the tracking servo and/or the focus servo is greater than or equal to a first predetermined frequency.