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Abstract

A data recording disk drive for use in a portable, battery-powered computer has several power-save modes of operation. The power-save modes are entered after a computed time since the last data read or write command. The computed time to enter a power-save mode is based on the computer user's real-time workload and is thus continuously varying during operation of the disk drive. The disk drive detects the current user workload by calculating the frequency of disk drive accesses and based on this history determines which of a plurality of power-save modes is appropriate and when to enter a power-save mode. Each disk drive read or write access is detected and used to compute a current access frequency. The current access frequency is compared to a previously calculated and continuously updated threshold frequency. The threshold frequency is representative of the access pattern, e.g., uniform or sporadic, and is computed from equations that include adjustable gain factors. The appropriate power-save mode is entered when the current access frequency falls below the threshold frequency. Intermediate power-save modes can be skipped, based on the detected access pattern. The disk drive can also adapt dynamically to varying workload situations, thereby saving more energy without degrading performance. This is accomplished by adjusting the gain factors in response to tracking the actual performance of the system, thereby changing the threshold frequency. The disk drive also determines when to exit a power-save mode without necessarily waiting for a user access.

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First Claim