Seek scheduling in a split actuator drive

Abstract

Systems and methods for scheduling the execution of disk access commands in a split-actuator hard disk drive are provided. In some embodiments, while a first actuator of the split actuator is in the process of performing a first disk access command (a victim operation), a second disk access command (an aggressor operation) is selected for and executed by a second actuator of the split actuator. The aggressor operation is selected from a queue of disk access commands for the second actuator, and is selected based on being the disk access command in the queue that can be initiated sooner than any other disk access command in the queue without disturbing the victim operation.

We claim: 
     
         1 . A disk drive comprising:
 a first actuator that controls an arm having a first head and extending over a first surface of a plurality of disk surfaces;   a second actuator that controls an arm having a second head and extending over a second surface of a plurality of disk surfaces other than the first surface; and   a controller configured to:   while the first actuator is in the process of performing a first disk access operation, select a second disk access operation from a queue of operations to be performed by the second actuator;   determine that a disturbance time of the second disk access operation coincides with at least a portion of a critical time of the first disk access operation;   in response to determining that the disturbance time coincides with at least a portion of the critical time, generate a modified second disk access operation that does not include a disturbance time that coincides with at least a portion of the critical time of the first disk access operation;   select as an operation for execution either the modified second disk access operation or a third disk access operation from the queue of operations to be performed by the second actuator; and   execute the operation for execution.   
     
     
         2 . The disk drive of  claim 1 , wherein generating the modified second disk access operation comprises modifying an input current profile of the second disk access operation. 
     
     
         3 . The disk drive of  claim 2 , wherein modifying the input current profile of the second disk access operation comprises reducing an absolute value of a maximum rate of change of input current in the input current profile to a value that is equal to or less than a threshold rate of change value. 
     
     
         4 . The disk drive of  claim 2 , wherein modifying the input current profile of the second disk access operation comprises reducing an absolute value of input current in the input current profile to a value that is equal to or less than a threshold input current value. 
     
     
         5 . The disk drive of  claim 2 , wherein modifying the input current profile of the second disk access operation comprises modifying an input current during at least one of an acceleration increase segment of the second disk access operation, a constant acceleration segment of the second disk access operation, an acceleration decrease segment of the second disk access operation, a deceleration increase segment of the second disk access operation, a constant deceleration segment of the second disk access operation, and a deceleration decrease segment of the second disk access operation. 
     
     
         6 . The disk drive of  claim 1 , wherein executing the operation for execution comprises executing the operation for execution prior to executing any other disk access operation from the queue of operations to be performed by the second actuator. 
     
     
         7 . The disk drive of  claim 1 , wherein the second disk access operation has an execution start time that occurs before an execution start time of the third disk access operation. 
     
     
         8 . The disk drive of  claim 7 , wherein the execution start time of the second disk operation corresponds to a first time at which the second head passes over an initial target sector of the second disk operation upon completion of a disk operation currently being performed by the second actuator and the execution start time of the third disk operation corresponds to a first time at which the second head passes over an initial target sector of the third disk operation upon completion of the disk operation currently being performed by the second actuator. 
     
     
         9 . The disk drive of  claim 1 , wherein being in the process of performing the first disk access operation comprises at least one of seeking the first head to a target track of the first disk access operation, positioning the first head over the target track, and having the first disk access operation designated as the next disk access operation to be performed with the first actuator. 
     
     
         10 . The disk drive of  claim 1 , wherein selecting as the operation for execution either the modified second disk access operation or a third disk access operation comprises:
 determining that an execution start time of the second disk access operation occurs during a seek operation of the modified second disk access operation; and   in response, selecting the third disk access operation as the command for execution.   
     
     
         11 . The disk drive of  claim 1 , wherein selecting as the operation for execution either the modified second disk access operation or a third disk access operation comprises:
 determining that an execution start time of the second disk access operation occurs during a seek operation of the modified second disk access operation;   in response, generating the third disk access operation by adding a disk access execution delay to the execution start time of the second disk access operation; and   selecting the third disk access operation as the operation for execution.   
     
     
         12 . The disk drive of  claim 11 , wherein adding the disk access execution delay to the execution start time of the second disk access operation comprises rotating the second surface until the second head is circumferentially colocated with an initial target sector of the second disk access operation while the head is positioned over a target track of the second disk access operation. 
     
     
         13 . The disk drive of  claim 1 , wherein the critical time of the first disk access operation comprises one of a time interval during which data are being read from the first surface with the first head and a time interval during which data are being written to the first surface with the first head. 
     
     
         14 . A method of selecting and executing disk access commands in a disk drive that includes a first actuator that controls an arm having a first head and a second actuator that controls an arm having a second head, the method comprising:
 while the first actuator is in the process of performing a first disk access operation, selecting a second disk access operation from a queue of operations to be performed by the second actuator;   determining that a disturbance time of the second disk access operation coincides with at least a portion of a critical time of the first disk access operation;   in response to determining that the disturbance time coincides with at least a portion of the critical time, generating a modified second disk access operation that does not include a disturbance time that coincides with at least a portion of the critical time of the first disk access operation;   selecting as an operation for execution either the modified second disk access operation or a third disk access operation from the queue of operations to be performed by the second actuator; and   executing the operation for execution.   
     
     
         15 . The method of  claim 14 , wherein generating the modified second disk access operation comprises modifying an input current profile of the second disk access operation. 
     
     
         16 . The method of  claim 14 , wherein executing the operation for execution comprises executing the operation for execution prior to executing any other disk access operation from the queue of operations to be performed by the second actuator. 
     
     
         17 . The method of  claim 14 , wherein the second disk access operation has an execution start time that occurs before an execution start time of the third disk access operation. 
     
     
         18 . The method of  claim 14 , wherein being in the process of performing the first disk access operation comprises at least one of seeking the first head to a target track of the first disk access operation, positioning the first head over the target track, and having the first disk access operation designated as the next disk access operation to be performed with the first actuator. 
     
     
         19 . The method of  claim 14 , wherein selecting as the operation for execution either the modified second disk access operation or a third disk access operation comprises:
 determining that an execution start time of the second disk access operation occurs during a seek operation of the modified second disk access operation; and   in response, selecting the third disk access operation as the command for execution.   
     
     
         20 . The method of  claim 14 , wherein the critical time of the first disk access operation comprises one of a time interval during which data are being read from the first surface with the first head and a time interval during which data are being written to the first surface with the first head.