Adaptive power management for hard disk drives
AssigneeMaxtor Corporation
InventorPeter T. McLean
Life of this patent
Estimating the term…
Abstract
A method of managing the power consumed by a hard disk drive in a portable computer. The first step consists of measuring the work load placed on the hard disk drive by a particular computer, a particular application and a particular user. The next step is to determine the average power consumed in the disk drive in the active state and in a lower power state for a series of wait times. The next step is to determine the total average power consumed by the disk drive for both states for the series of wait times. The next step is to determine the wait time at which the total average power consumed by the disk drive in minimum. The final step is to set the wait time at which the disk drive operates to the previously determined minimum wait time.
Claims31
A method of managing the power consumed by a disk drive in a host computer system as a result of a work load placed on said disk drive by said host computer, said method comprising the following steps:
- providing a host that sends access requests to a disk drive;
- providing a disk drive that is operatively connected to said host, is capable of storing data, and is capable of transferring data with said host in response to access requests by said host, wherein said disk drive is capable of operating in at least a first state in which said disk drive responds to an access request from said host in a first time and consumes a known first power and wherein after a wait time shifting to a second state in which said disk drive responds to an access request from said host more slowly than said first time in said first state and consumes a known second power which is less than said known first power;
- collecting data on access requests between said host and said disk drive that provides information on the work load placed upon said disk drive by said host;
- wherein the work load associated with the access requests by said host to said disk drive is likely to be unique relative to the work load associated with the access requests that would be placed upon said disk drive by another arbitrarily chosen host;
- and
- using said data to determine a wait time for shifting said disk drive from said first state to said second state such that the power consumed by said disk drive to respond to access requests made by said host tends toward a minimum, based upon the work load associated with the access requests between said host and said disk drive.
A method of managing the power consumed by a hard disk drive in a host computer system as a result of a work load placed on said hard disk drive by said host computer and wherein said hard disk drive is capable of operating in at least a first state in which the hard disk drive responds to an access request from said host in a minimum time and consumes a known maximum power and wherein after a wait time shifting to a second state in which said hard disk drive responds to an access from said host more slowly than in said first state and consumes a known second power which is less than said maximum power, said method comprising the following steps:
- collecting data that provides information on the work load placed upon said hard disk drive by said host;
- using said data to determine a wait time such that the total power consumed by said hard disk drive to respond to substantially all access requests made by said host is minimized;
- wherein said step of collecting data that provides information on the work load placed on said hard disk drive by said host computer includes determining the number of host computer access requests made from said first operating state and said second operating state as a function of wait time.
A method of managing the power consumed by a hard disk drive in a host computer system as a result of a work load placed on said hard disk drive by said host computer and wherein said hard disk drive is capable of operating in the active state in which the hard disk drive responds to an access request from said host in a minimum time and consumes a known maximum power and wherein after a wait time shifting to the sleep state in which said hard disk drive responds to an access from said host more slowly than in said active state and consumes a known sleep power which is less than said maximum power, said method comprising the following steps:
- taking a first sample of the number of requests from said host that are responded to from said active state as a percent of the total number of requests responded to by said disk drive for a first wait time;
- from said number of requests from said host that are responded to from said active state in said first sample, determining an active average power value required to respond to requests for access from said host from said active state for said first wait time;
- taking a second sample of the number of requests from said host that are responded to from said active state as a percent of the total number of requests responded to by said disk drive for a second wait time equal to said first wait time plus a predetermined time increment;
- from said number of requests from said host that are responded to from said active state in said second sample, determining a second average power value required to respond to access requests from said host from said active state for said second wait time;
- determining the difference between said first and second average power values required to respond to requests for access from said host from said active state;
- from said first sample of requests, determining the number of requests from said host that are responded to from said sleep state as a percent of the total number of requests responded to by said disk drive for a first wait time by subtracting from one the percent of the total number of requests responded to by said disk drive from said active state for a first wait time;
- from said number of requests from said host that are responded to from said sleep state from said first sample, determining a first average power value required to respond to requests for access from said host from said active state for said first wait time;
- from said number of requests from said host that are responded to from said sleep state in said second sample, determining a second average power required to respond to access requests from said host from said active state for said second wait time;
- determining the difference between said first and second average power values required to respond to requests for access from said host from said sleep state;
- determining if the wait time at which said first sample was taken is greater than the wait time at which said second sample was taken;
- if yes, subtracting the difference between said active and sleep average power values required to respond to requests for access from said host from said sleep state from the difference between said active and sleep average powers values required to respond to requests for access from said host from said active state to form a power difference;
- if no, subtracting the difference between said sleep and active average power values required to respond to requests for access from said host from said active state from the difference between said active and sleep average powers values required to respond to requests for access from said host from said sleep state to form said power difference;
- if said average power difference is greater than zero by more than a predetermined minimum power difference, iterate the method by taking a third sample of the number of requests from said host that are responded to from said active state as a percent of the total number of requests responded to by said disk drive for a third wait time equal to said second wait time minus a predetermined increment;
- if said average power difference is less than zero by more than a predetermined minimum power difference, iterate the method by taking a third sample of the number of requests from said host that are responded to from said active state as a percent of the total number of requests responded to by said disk drive for a third wait time equal to said second wait time plus a predetermined increment;
- and
- if said average power difference is equal to or less than said predetermined minimum power difference value, causing said hard disk drive to shift from said active state to said sleep state at said sleep wait time.
A method of managing the power consumed by a hard disk drive in a host computer system as a result of a work load placed on said hard disk drive by said host computer and wherein said hard disk drive is capable of operating in a first state in which the hard disk drive responds to an access request from said host in a minimum time and consumes a known maximum power and wherein after a wait time shifting to a second state in which said hard disk drive responds to an access from said host more slowly than in said first state and consumes a known second power which is less than said maximum power, said method comprising the following steps:
- collecting statistics on the arrival time of requests from said host;
- using said statistics to calculate a first power function corresponding to the average power required to respond to a request from said host while said hard disk drive is in said first state as a function of wait time;
- using said statistics to calculate a second power function corresponding to the average power required to respond to a request from said host while said hard disk drive is in said second state as a function of wait time;
- summing said first and second power function to create a third power function corresponding to the total average power consumed by said hard disk drive to respond to substantially all access requests made by said host as a function of wait time;
- determining the wait time for which said total average power is a minimum;
- and
- causing said hard disk drive to shift from said first to said second state at said wait time when the total average power is a minimum.
A disk drive for responding to access requests from a host and having adaptive power consumption tailored to the work load associated with responding to access requests by the host, said disk drive comprising:
- means for operating in at least a first state in which said disk drive responds to an access request from the host in a first time and consumes a known first power and wherein after a wait time shifting to a second state in which said disk drive responds to an access request from the host more slowly than said first time in said first state and consumes a known second power which is less than said known first power;
- means for collecting data on the work load of said disk drive responding to access requests by the host, wherein the work load placed upon said disk drive by the host is likely to be unique relative to the work load placed upon the disk drive by another arbitrarily chosen host;
- and
- means for determining a wait time, from said data, for shifting said disk drive from said first state to said second state such that the power consumed by said disk drive to respond to access requests provided by the host tends toward a minimum, based upon the work load associated with responding to access requests by the host.
Dependencies are inferred from the claim text.