FLASH-AWARE STORAGE OPTIMIZED FOR MOBILE AND EMBEDDED DBMS ON NAND FLASH MEMORY

• US 20080288713A1
• Filed: 05/16/2007
• Published: 11/20/2008
• Est. Priority Date: 05/16/2007
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Yoo, HyungGook, Ko, BongSoo, Kang, SongHee, LEE, SangCheol
• Granted Patent: US 7,856,522 B2
• 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 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/214 Solid state disk
• CPC Class Codes: G06F 2212/2146 being detachable, e.g.. USB memory
• CPC Class Codes: G06F 2212/465 Structured object, e.g. database record
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7202 Allocation control and policies

Abstract

Reliable storage for database management systems (DBMS) running on memory devices such as NAND type flash memory utilizes minimum I/O overhead and provides maximum data durability. A virtual page map is utilized between the flash memory and a page access component to record changes to the DBMS pages and prevent overwriting or data loss. There is no need for journaling and logging, and performance is increased by reducing the write and erase counts on the flash memory. The logical page numbers of the DBMS are mapped to physical page numbers in the page map, such that the virtual page map allocates an available page from the physical pages when changes to a page occur, and the updated information is stored in the allocated page. The allocated page number is mapped to the logical page number of the original page, thus maintaining a modified page representation while preventing physical in-place updates.

Claims

1. A system for managing data on a mobile device, comprising:

a flash memory component in communication with the mobile device and operable to store data;

a cache memory component operable to store a copy of at least a portion of the data in temporary storage on the mobile device;

a database management component on the mobile device and operable to manage data in pages;

an access component operable to provide access to the data stored in the pages; and

a virtual page map component operable to maintain mappings of logical page numbers of the database management component with physical page numbers in the flash memory component, whereby updates to the data are made using the logical page number to identify the page in cache memory, and the virtual page map is operable to provide the physical page number to be used in updating the physical page stored on the flash memory component after updates to the corresponding page in cache memory are complete.

2. A system according to claim 1, wherein:

the flash memory component is removable from the mobile device.

3. A system according to claim 1, wherein:

the virtual page map component is further operable to flush the data from the page in the cache memory component only after the updates are committed in the flash memory component.

4. A system according to claim 1, wherein:

the virtual page map component is operable to determine whether a physical page number is mapped to a logical page number for an update, and further operable to allocate a physical page number if necessary.

5. A system according to claim 1, wherein:

the flash memory component is NAND-type flash memory.

6. A system according to claim 1, wherein:

the access component is operable to provide access to the data for at least one of applications executing on the mobile device and external devices in communication with the mobile device.

7. A system according to claim 1, wherein:

the virtual map component is further operable to allocate an available physical page when changes occur to a page in the cache memory component and store updated data in the allocated page.

8. A system according to claim 7, wherein:

the virtual map component is further operable to map the logical page number to the allocated page.

9. A system according to claim 1, wherein:

the virtual map page utilizes a bitmap structure.

10. A system according to claim 1, wherein:

the virtual map page is divided into segments, and each segment is operable to be flushed when new storage for the data of that segment is allocated.

11. A system according to claim 1, wherein:

the access component is further operable to update the virtual page map component with appropriate logical and physical page data.

12. A system according to claim 1, wherein:

the virtual page map is further operable to mark a logical page available for allocation after that logical page has been updated at least twice.

13. A method of managing data on a mobile device, comprising:

storing data in physical pages in a flash memory component on the mobile device;

storing a copy of at least a portion of the data in logical pages in a cache memory component on the mobile device;

providing access to the data stored in the cache memory component and the flash memory component using an access component; and

maintaining mappings of logical page numbers for the logical pages in the cache memory component with physical page numbers for physical pages in the flash memory component in a virtual page map component, whereby updates to the data are made using the logical page number to identify the logical page in cache memory, and the virtual page map is operable to provide the physical page number to be used in updating the physical page stored on the flash memory component after updates to the corresponding page in cache memory are complete.

14. A method according to claim 13, further comprising:

managing the storing of data using a database management system.

15. A method according to claim 13, further comprising:

flushing the data from the logical page in the cache memory component only after the updates are committed to a physical page in the flash memory component.

16. A method according to claim 13, further comprising:

determining whether a physical page number is mapped to a logical page number for an update to the data.

17. A method according to claim 16, further comprising:

allocating a physical page number if a physical page number is not mapped to the logical page number for the update.

18. A method according to claim 13, further comprising:

providing access to the data for at least one of applications executing on the mobile device and external devices in communication with the mobile device.

19. A method according to claim 13, further comprising:

allocating an available physical page when changes occur to a logical page in the cache memory component and storing updated data in the allocated physical page.

20. A computer program product embedded in a computer readable medium for managing data on a mobile device, comprising:

program code for storing data in physical pages in a flash memory component on the mobile device;

program code for storing a copy of at least a portion of the data in logical pages in a cache memory component on the mobile device;

program code for providing access to the data stored in the cache memory component and the flash memory component using an access component; and

program code for maintaining mappings of logical page numbers for the logical pages in the cache memory component with physical page numbers for physical pages in the flash memory component in a virtual page map component, whereby updates to the data are made using the logical page number to identify the logical page in cache memory, and the virtual page map is operable to provide the physical page number to be used in updating the physical page stored on the flash memory component after updates to the corresponding page in cache memory are complete.