MANAGING DATA PLACEMENT ON FLASH-BASED STORAGE BY USE

• US 20120317337A1
• Filed: 06/09/2011
• Published: 12/13/2012
• Est. Priority Date: 06/09/2011
• Status: Abandoned Application

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Johar, Akshay, Aasheim, Jered
• Application Number:
  US13/156,361
• Publication Number:
  US 20120317337A1
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles

Abstract

A storage placement system is described herein that uses an operating system'"'"'s knowledge related to how data is being used on a computing device to more effectively communicate with and manage flash-based storage devices. Cold data that is not frequently used can be differentiated from hot data clusters and placed in worn areas, while hot data that is frequently used can be kept readily accessible. By clustering hot data together and cold data in separate sections, the system is better able to perform wear leveling and prolong the usefulness of the flash medium. Storage of data in the cloud or other storage can intelligently persist data in a location for a short time before coalescing data to write in a block. Thus, the system leverages the operating system'"'"'s knowledge of how data has been and will be used to place data on flash-based storage devices in an efficient way.

Claims

1. A computer-implemented method for writing data to a selected location on a flash-based storage device, the method comprising:

receiving a request to write data to a flash-based storage device;

qualifying a frequency of access associated with the data to be written to the flash-based storage device;

selecting a data placement location on the flash based storage device for the data to be written based on the qualified frequency of access of the data;

sending placement information to the flash-based storage device, indicating the selected data placement location for the data to be written; and

storing the requested data at the selected data placement location on the flash-based storage device,

wherein the preceding steps are performed by at least one processor.

2. The method of claim 1 wherein receiving the request comprises a request received by an operating system in which the method is implemented as a file system driver, by firmware, or directly in hardware to manage placement of data on flash-based devices.

3. The method of claim 1 wherein receiving the request comprises receiving additional information about the data to be written that describes a purpose for the data.

4. The method of claim 1 wherein receiving the request comprises receiving additional information about the data to be written that describes a frequency of access needed for the data.

5. The method of claim 1 wherein qualifying the data comprises determining how frequently the data will be read and how frequently the data will be written.

6. The method of claim 1 wherein qualifying the data comprises qualifying the data based on historical access patterns for a file system location associated with the data.

7. The method of claim 1 wherein qualifying the data comprises qualifying the data based on meta-information received with the request.

8. The method of claim 1 wherein qualifying the data comprises qualifying the data based on well-known operating system implementation information.

9. The method of claim 1 wherein selecting the placement location comprises informing the device of the qualified frequency of access of the data and allowing the device to select a location for the data.

10. The method of claim 1 wherein selecting the placement location comprises identifying a worn block as a suitable location for data that will not be written again frequently.

11. The method of claim 1 wherein selecting the placement location comprises selecting a location on a separate, secondary storage device for holding data that is less suitable for the flash-based storage device.

12. The method of claim 1 wherein sending placement information comprises providing the information to the device as a parameter to a command for writing data to the drive.

13. A computer system for managing data placement on flash-based storage by use, the system comprising:

a processor and memory configured to execute software instructions embodied within the following components;

a flash-based storage device that includes at least some flash-based memory for non-volatile data storage;

a data qualification component that qualifies data received by an operating system by a frequency with which the data is likely to be written, wherein data that is written often is called hot data and data that is written infrequently is called cold data;

a data monitoring component that monitors data read and written by an operating system and stores historical use information for data;

a data placement component that determines one or more locations to which data to be written to the flash-based storage device will be written among all of the locations available from the device; and

a storage communication component that provides an interface between the other components of the system and the flash-based storage device.

14. The system of claim 13 wherein the data qualification component accesses historical data access information acquired by the data monitoring component, as well as using specific-knowledge implicitly or explicitly supplied by the operating system describing particular data'"'"'s purpose.

15. The system of claim 13 wherein the data monitoring component monitors which files are used under various conditions and at various times, which files are accessed together, and how recoverable a particular data chunk is.

16. The system of claim 13 wherein the data placement component uses the qualification of data determined by the data qualification component to determine where data should be located, and uses the storage communication component to access drive information tracked by the drive firmware or hardware.

17. The system of claim 13 wherein the data placement component selects a location that is good for both the longevity of the drive and a level of performance appropriate for the data to be written.

18. The system of claim 13 wherein the data placement component selects locations with increasingly longer latencies as the data'"'"'s access frequency decreases.

19. The system of claim 13 further comprising a failure management component that handles access and/or movement of data to and from the flash-based storage device as the device is approaching its wear limit based on a difficulty of recovering data if lost.

20. A computer-readable storage medium comprising instructions for controlling a computer system to select a placement location for data to be written on a flash-based storage device, wherein the instructions, upon execution, cause a processor to perform actions comprising:

receiving information that qualifies an access frequency of data to be written to the flash-based storage device;

upon determining that the data will be infrequently written,

identifying one or more worn locations of the flash-based storage device at which the infrequently written data can reside to retain less worn locations available for other data; and

selecting one of the identified more worn locations to which to write the data; and

upon determining that the data will be frequently written,

locating any other frequently written data related to the data to be written; and

selecting a less worn location near the other frequently written data at which to place the data to be written; and

reporting the selected placement to a component for writing the data to the selected location.