Media based cache for data storage device

• US 9,959,052 B1
• Filed: 09/17/2015
• Issued: 05/01/2018
• Est. Priority Date: 09/17/2015
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Xu, Jun, Xi, Wei, Guo, Guoxiao, Wang, Jianyi, Niu, Junpeng
• Primary Examiner(s): Bansal, Gurtej
• Application Number:
  US14/857,467
• Time in Patent Office: 957 Days
• CPC Class Codes: G06F 12/0871 Allocation or management of cache space
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/313 In storage device
• CPC Class Codes: G06F 2212/462 Track or segment
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0676 Magnetic disk device

Abstract

Write commands are received for a Data Storage Device (DSD) to store write data in a plurality of corresponding write locations on at least one disk of the DSD. At least a portion of the write data is cached in at least one Media Based Cache (MBC) region of the at least one disk based on a write cache policy for determining which write data is eligible for caching in the at least one MBC region. The at least one MBC region is used to cache data to be stored in other locations on the at least one disk. During an active time period when host commands are performed on the at least one disk, a portion of an I/O bandwidth for performing commands is used to copy the at least a portion of the write data to corresponding write locations of the plurality of corresponding write locations.

Claims

1. A Data Storage Device (DSD), comprising:

at least one disk including at least one Media Based Cache (MBC) region for caching data to be stored in other locations on the at least one disk; and

a controller configured to;

receive a plurality of write commands to store write data in a plurality of corresponding write locations on the at least one disk;

cache at least a portion of the write data in the at least one MBC region based on a write cache policy for determining which write data is eligible for caching in the at least one MBC region; and

during an active time period when host commands are performed on the at least one disk, reserve a portion of an I/O bandwidth for performing commands to copy the at least a portion of the write data to corresponding write locations of the plurality of corresponding write locations, wherein the I/O bandwidth includes a rate of operations performed on the at least one disk or a data transfer rate for performing operations on the at least one disk, and wherein the commands to copy the at least a portion of the write data are performed from a command queue including other commands received from a host to be performed on the at least one disk during the active time period.

2. The DSD of claim 1, wherein the controller is further configured to determine an order for caching data of the at least a portion of the write data in the at least one MBC region based on one or more destage conditions for caching the data in the at least one MBC region.

3. The DSD of claim 1, further comprising a cache memory, and wherein the controller is further configured to:

store another portion of the write data in the cache memory that meets the write cache policy for determining which write data is eligible for caching in the at least one MBC region; and

write the another portion of the write data to other corresponding write locations of the plurality of corresponding write locations without caching the another portion of the write data in the at least one MBC region.

4. The DSD of claim 1, further comprising at least one head for writing and reading data on the at least one disk, and wherein the controller is further configured to select an MBC region of the at least one MBC region in which to cache the at least a portion of the write data based on a current location of the at least one head or a predicted position of the at least one head.

5. The DSD of claim 1, wherein the controller is further configured to determine an order for copying the at least a portion of the write data to the corresponding write locations based on an amount of time that a host command has been pending in the command queue for performance on the at least one disk.

6. The DSD of claim 1, wherein the disk includes a plurality of tracks for storing data, and wherein during the active time period, the controller is further configured to determine a number of tracks to be included in an MBC region of the at least one MBC region.

7. The DSD of claim 1, wherein the controller is further configured to reassign at least a portion of the at least one MBC region as a user data region for storing user data instead of caching data to be stored in other locations on the at least one disk.

8. The DSD of claim 1, wherein the controller is further configured to adjust a rate of copying the at least a portion of the write data to the corresponding write locations to increase or decrease a number of pending commands for performing on the at least one disk.

9. The DSD of claim 1, further comprising a cache memory, and wherein the controller is further configured to store the at least a portion of the write data in the cache memory before caching the at least a portion of the write data in the at least one MBC region.

10. The DSD of claim 9, wherein in copying the at least a portion of the write data to the corresponding write locations, the controller is further configured to copy the at least a portion of the write data from the cache memory to the corresponding write locations.

11. The DSD of claim 9, wherein the controller is further configured to:

store the at least a portion of the write data in one or more segments of the cache memory; and

select a segment of the one or more segments to cache the write data stored in the selected segment in the at least one MBC region based on one or more destage conditions, and

wherein the one or more destage conditions include at least one of an amount of write data stored in the selected segment, an amount of time that the write data has been stored in the selected segment, and a number of pending write commands with write data waiting to be stored in the one or more segments of the cache memory.

12. The DSD of claim 11, wherein the controller is further configured to promote a segment of the cache memory from an active group of segments storing write data to a prestage group of segments from which the controller selects the selected segment to cache the write data stored in the selected segment.

13. The DSD of claim 1, wherein the disk includes a plurality of tracks for storing data, and wherein during the active time period, the controller is further configured to assign one or more tracks as a new MBC region of the at least one MBC region.

14. The DSD of claim 13, further comprising at least one head for writing and reading data on the at least one disk, and wherein the controller is further configured to assign the one or more tracks as the new MBC region based on a current location or a predicted location of the at least one head.

15. The DSD of claim 1, wherein the controller is further configured to maintain MBC information indicating one or more locations for the at least one MBC region on the at least one disk.

16. The DSD of claim 15, wherein the MBC information further indicates whether data stored in the at least one MBC region is valid data.

17. A method for operating a Data Storage Device (DSD) including at least one disk for storing data, the method comprising:

receiving a plurality of write commands to store write data in a plurality of corresponding write locations on the at least one disk;

caching at least a portion of the write data in at least one Media Based Cache (MBC) region of the at least one disk based on a write cache policy for determining which write data is eligible for caching in the at least one MBC region, wherein the at least one MBC region is used to cache data to be stored in other locations on the at least one disk; and

during an active time period when host commands are performed on the at least one disk, reserving a portion of an I/O bandwidth for performing commands to copy the at least a portion of the write data to corresponding write locations of the plurality of corresponding write locations, wherein the I/O bandwidth includes a rate of operations performed on the at least one disk or a data transfer rate for performing operations on the at least one disk, and wherein the commands to copy the at least a portion of the write data are performed from a command queue including other commands received from a host to be performed on the at least one disk during the active time period.

18. The method of claim 17, further comprising determining an order for caching data of the at least a portion of the write data in the at least one MBC region based on one or more destage conditions for caching the data in the at least one MBC region.

19. The method of claim 17, further comprising:

storing another portion of the write data in a cache memory of the DSD that meets the write cache policy for determining which write data is eligible for caching in the at least one MBC region; and

writing the another portion of the write data to other corresponding write locations of the plurality of corresponding write locations without caching the another portion of the write data in the at least one MBC region.

20. The method of claim 17, wherein the DSD includes at least one head for writing and reading data on the at least one disk, and wherein the method further comprises selecting an MBC region of the at least one MBC region in which to cache the at least a portion of the write data based on a current location of the at least one head or a predicted position of the at least one head.

21. The method of claim 17, further comprising determining an order for copying the at least a portion of the write data to the corresponding write locations based on an amount of time that a host command has been pending in the command queue for performance on the at least one disk.

22. The method of claim 17, wherein the disk includes a plurality of tracks for storing data, and wherein during the active time period, the method further comprises determining a number of tracks to be included in an MBC region of the at least one MBC region.

23. The method of claim 17, further comprising reassigning at least a portion of the at least one MBC region as a user data region for storing user data instead of caching data to be stored in other locations on the at least one disk.

24. The method of claim 17, further comprising adjusting a rate of copying the at least a portion of the write data to the corresponding write locations to increase or decrease a number of pending commands for performing on the at least one disk.

25. The method of claim 17, further comprising storing the at least a portion of the write data in a cache memory of the DSD before caching the at least a portion of the write data in the at least one MBC region.

26. The method of claim 25, wherein in copying the at least a portion of the write data to the corresponding write locations, the method further comprises copying the at least a portion of the write data from the cache memory to the corresponding write locations.

27. The method of claim 25, further comprising:

storing the at least a portion of the write data in one or more segments of the cache memory; and

selecting a segment of the one or more segments to cache the write data stored in the selected segment in the at least one MBC region based on one or more destage conditions, and

wherein the one or more destage conditions include at least one of an amount of write data stored in the selected segment, an amount of time that the write data has been stored in the selected segment, and a number of pending write commands with write data waiting to be stored in the one or more segments of the cache memory.

28. The method of claim 27, further comprising promoting a segment of the cache memory from an active group of segments storing write data to a prestage group of segments from which the selected segment is selected to cache the write data stored in the selected segment.

29. The method of claim 17, wherein the disk includes a plurality of tracks for storing data, and wherein during the active time period, the method further comprises assigning one or more tracks as a new MBC region of the at least one MBC region.

30. The method of claim 29, further comprising at least one head for writing and reading data on the at least one disk, and wherein the method further comprises assigning the one or more tracks as the new MBC region based on a current location or a predicted location of the at least one head.

31. The method of claim 17, further comprising maintaining MBC information indicating one or more locations for the at least one MBC region on the at least one disk.

32. The method of claim 31, wherein the MBC information further indicates whether data stored in the at least one MBC region is valid data.

33. A non-transitory computer readable medium storing computer-executable instructions for operating a Data Storage Device (DSD) including at least one disk for storing data, wherein when the computer-executable instructions are executed by a controller of the DSD, the computer-executable instructions cause the controller to:

receive a plurality of write commands to store write data in a plurality of corresponding write locations on the at least one disk;

cache at least a portion of the write data in at least one Media Based Cache (MBC) region of the at least one disk based on a write cache policy for determining which write data is eligible for caching in the at least one MBC region, wherein the at least one MBC region is used to cache data to be stored in other locations on the at least one disk; and

during an active time period when host commands are performed on the at least one disk, reserve a portion of an I/O bandwidth for performing commands to copy the at least a portion of the write data to corresponding write locations of the plurality of corresponding write locations, wherein the I/O bandwidth includes a rate of operations performed on the at least one disk or a data transfer rate for performing operations on the at least one disk, and wherein the commands to copy the at least a portion of the write data are performed from a command queue including other commands received from a host to be performed on the at least one disk during the active time period.