Adaptively modifying pre-read operations within a rotating media storage device
View Patent ↗A rotating media storage device (RMSD) that adaptively modifies pre-read operations is disclosed. The RMSD schedules a pre-read data segment on a second track of disk, commands a movable head to seek to the second track, and if an on-track condition is not met for the scheduled pre-read data segment, modifies the pre-read operation. In one example, modifying the pre-read operation includes canceling the pre-read operation and then performing a read data operation.
1. A rotating media storage device (RMSD) connectable to a host computer, the RMSD comprising:
a disk including at least a first track and a second track;
a moveable head;
a cache memory to store data segments from the disk that have been previously read; and
a microprocessor for controlling operations in the RMSD including seek operations and read operations that include pre-read operations to read pre-read data, read data operations for reading read data, and post-read operations to read post-read data, wherein the reading of the pre-read data is adaptively modified such that a remaining portion of data segments of the pre-read data is read and the read data and the post-read data are read, within one disk drive revolution, the microprocessor under the control of a program to:
a. schedule a forecasted pre-read data portion on the second track, wherein the scheduled pre-read data portion includes a plurality of data segments;
b. command the moveable head to seek to the second track;
c. determine if an on-track condition is physically met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if so, perform the pre-read operation for the scheduled pre-read data portion; and
d. determine if the on-track condition cannot be met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if not, adaptively modify the scheduled pre-read data portion based on a calculation of a remaining portion of the scheduled pre-read data portion to be read based upon servo position information from the servo controller that determines a physical component that includes a number of data segments that are readable from the scheduled pre-read data portion and based upon a caching component associated with determining whether, based upon rules of a read caching algorithm that determine if coherency factors are met, the read caching algorithm would support reading the remaining portion of the pre-read data, wherein if both the physical component and the caching component are satisfied, the remaining portion of data segments of the scheduled pre-read data portion is read and the read data and the post-read data are read, within one disk drive revolution.
2. The RMSD of claim 1 , wherein, if the physical component or the caching component is not satisfied, adaptively modifying the scheduled pre-read data portion includes canceling the pre-read operation and then performing the read data operation to read the read data.
3. The RMSD of claim 1 , wherein, the physical component includes a pre-determined minimum number of data segments that are required to be read from the scheduled pre-read data portion.
4. In a rotating media storage device (RMSD) connectable to a host computer, the RMSD having a disk including at least a first track and a second track, a moveable head, a servo controller, a cache memory to store data segments from the disk that have been previously read and a microprocessor for controlling operations in the RMSD including seek operations and read operations that include pre-read operations to read pre-read data, read data operations for reading read data, and post-read operations to read post-read data, wherein the reading of the pre-read data is adaptively modified such that a remaining portion of data segments of the pre-read data is read and the read data and the post-read data are read, within one disk drive revolution, a method of efficiently switching between a read operation on the first track and a read operation on the second track, the method comprising the steps of:
a. scheduling a forecasted pre-read data portion on the second track, wherein the scheduled pre-read data portion includes a plurality of data segments;
b. commanding the moveable head to seek to the second track;
c. determining if an on-track condition is physically met for the scheduled pre-read data portion based upon servo position information from the servo controller, and if so, performing the pre-read operation for the scheduled pre-read data portion; and
d. determining if the on-track condition cannot be met for the scheduled pre-read data portion based upon servo position information from the servo controller, and if not, adaptively modifying the scheduled pre-read data portion based on a calculation of a remaining portion of the scheduled pre-read data portion to be read based upon servo position information from the servo controller that determines a physical component that includes a number of data segments that are readable from the scheduled pre-read data portion and based upon a caching component associated with determining whether, based upon rules of a read caching algorithm that determine if coherency factors are met, the read caching algorithm would support reading the remaining portion of the pre-read data, wherein if both the physical component and the caching component are satisfied, the remaining portion of data segments of the scheduled pre-read data portion is read and the read data and the post-read data are read, within one disk drive revolution.
5. The method of claim 4 , wherein, if the physical component or the caching component is not satisfied, adaptively modifying the scheduled pre-read data portion includes canceling the pre-read operation and then performing the read data operation to read the read data.
6. The method of claim 4 , wherein, the physical component includes a pre-determined minimum number of data segments that are required to be read from the scheduled pre-read data portion.
7. A computer system comprising a host computer and a rotating media storage device (RMSD), the RMSD further comprising:
a disk including at least a first track and a second track;
a moveable head;
a cache memory to store data segments from the disk that have been previously read; and
a microprocessor for controlling operations in the RMSD including seek operations and read operations that include pre-read operations to read pre-read data, read data operations for reading read data, and post-read operations to read post-read data, wherein the reading of the pre-read data is adaptively modified such that a remaining portion of data segments of the pre-read data is read and the read data and the post-read data are read, within one disk drive revolution, the microprocessor under the control of a program to:
a. schedule a forecasted pre-read data portion on the second track, wherein the scheduled pre-read data portion includes a plurality of data segments;
b. command the moveable head to seek to the second track;
c. determine if an on-track condition is physically met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if so, perform the pre-read operation for the scheduled pre-read data portion; and
d. determine if the on-track condition cannot be met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if not, adaptively modify the scheduled pre-read data portion based on a calculation of a remaining portion of the scheduled pre-read data portion to be read based upon servo position information from the servo controller that determines a physical component that includes a number of data segments that are readable from the scheduled pre-read data portion and based upon a caching component associated with determining whether, based upon rules of a read caching algorithm that determine if coherency factors are met, the read caching algorithm would support reading the remaining portion of the pre-read data, wherein if both the physical component and the caching component are satisfied, the remaining portion of data segments of the scheduled pre-read data portion is read and the read data and the post-read data are read, within one disk drive revolution.
8. The RMSD of claim 7 , wherein, if the physical component or the caching component is not satisfied, adaptively modifying the scheduled pre-read data portion includes canceling the pre-read operation and then performing the read data operation to read the read data.
9. The RMSD of claim 1 , wherein, the physical component includes a pre-determined minimum number of data segments that are required to be read from the scheduled pre-read data portion.