Power state change in disk drive based on disk access history

Abstract

A data storage device that includes a magnetic storage device selects one or more power states of the magnetic storage device based on a time interval since a most recent time data has been read from or written to the magnetic storage device. The power state of the magnetic storage device can be changed from a higher power consumption state to a lower power consumption state when the time interval exceeds a predetermined value. The power consumption state may be changed from an active servo state to an intermediate power consumption state, a park state, and/or a standby state, depending on the time elapsed since the most recent time data has been read from or written to the magnetic storage device.

We claim: 
     
         1 . A method of power management in a data storage device that includes a magnetic storage device, the method comprising:
 measuring a time interval since a most recent time data has been read from or written to the magnetic storage device; and   in response to the time interval exceeding a predetermined value, changing a current power consumption state of the magnetic storage device to a lower power consumption state.   
     
     
         2 . The method of  claim 1 , wherein the time interval measured is a time interval since a most recent time data has been read from or written to the magnetic storage device to satisfy a host command. 
     
     
         3 . The method of  claim 2 , wherein the current power consumption state comprises an active servo state and the lower power consumption state comprises an intermediate power consumption state that uses less power than the active servo state and more power than a parked state. 
     
     
         4 . The method of  claim 3 , wherein the intermediate power consumption state comprises a float state in which a servo system of the magnetic storage device is not used to provide continuous position control of a read/write head of the magnetic storage device. 
     
     
         5 . The method of  claim 3 , wherein the intermediate power consumption state comprises a low-frequency servo state in which a servo system of the magnetic storage device provides position control of a read/write head of the magnetic storage device using no more than a portion of the servo wedges on a storage disk of the magnetic storage device. 
     
     
         6 . The method of  claim 1 , wherein the current power consumption state comprises an intermediate power consumption state that uses less power than the active servo state and more power than a parked state. 
     
     
         7 . The method of  claim 6 , wherein the lower power consumption state comprises one of a standby state in which a storage disk of the magnetic storage device is not spinning and a parked state in which a read/write head of the magnetic storage device is parked. 
     
     
         8 . The method of  claim 1 , wherein the current power consumption state comprises a parked state in which a read/write head of the magnetic storage device is parked. 
     
     
         9 . The method of  claim 8 , wherein the lower power consumption state comprises a standby state in which a storage disk of the magnetic storage device is not spinning. 
     
     
         10 . The method of  claim 1 , further comprising, during the time interval in which the magnetic storage device is not accessed:
 receiving one or more commands; and   satisfying the one or more commands using at least one of a volatile solid-state memory of the data storage device and a non-volatile solid-state memory device of the data storage device.   
     
     
         11 . A data storage device, comprising:
 a magnetic storage device; and   a controller configured to:
 measure a time interval since a most recent time data has been read from or written to the magnetic storage device; and 
 in response to the time interval exceeding a predetermined value, change a current power consumption state of the magnetic storage device to a lower power consumption state. 
   
     
     
         12 . The data storage device of  claim 11 , wherein the time interval measured is a time interval since a most recent time data has been read from or written to the magnetic storage device to satisfy a host command. 
     
     
         13 . The data storage device of  claim 12 , wherein the current power consumption state comprises an active servo state and the lower power consumption state comprises an intermediate power consumption state that uses less power than the active servo state and more power than a parked state. 
     
     
         14 . The data storage device of  claim 11 , wherein the current power consumption state comprises an intermediate power consumption state that uses less power than the active servo state and more power than a parked state. 
     
     
         15 . The data storage device of  claim 14 , wherein the lower power consumption state comprises one of a standby state in which a storage disk of the magnetic storage device is not spinning and a parked state in which a read/write head of the magnetic storage device is parked. 
     
     
         16 . The data storage device of  claim 11 , wherein the current power consumption state comprises a parked state in which a read/write head of the magnetic storage device is parked. 
     
     
         17 . The data storage device of  claim 16 , wherein the lower power consumption state comprises a standby state in which a storage disk of the magnetic storage device is not spinning. 
     
     
         18 . The data storage device of  claim 11 , wherein the controller is further configured to, during the time interval in which the magnetic storage device is not accessed:
 receive one or more commands; and   satisfy the one or more commands using one of a volatile solid-state memory of the data storage device, a non-volatile solid-state memory device of the data storage device, and a combination of both.   
     
     
         19 . A data storage device, comprising:
 a magnetic storage device;   a non-volatile solid-state device; and   a controller configured to:
 determine that a portion of the non-volatile solid-state device used to store data that are not also stored on the magnetic storage device is greater than a predetermined value; 
 change a power state of the magnetic storage device from an initial power state to an active servo state, the initial power state being a lower power state than the active servo state; and 
 control the writing to the magnetic storage device of at least a portion of the data that are not also stored on the magnetic storage device. 
   
     
     
         20 . The data storage device of  claim 19 , wherein the controller is further configured to, while the magnetic storage device is at the initial power state, control the writing of data from a host device to the non-volatile solid-state device.