METHOD FOR MANAGING PARTITIONS IN A STORAGE DEVICE

• US 20090043984A1
• Filed: 10/16/2008
• Published: 02/12/2009
• Est. Priority Date: 06/29/2005
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Sabet-Sharghi, Farshid, Holtzman, Michael, McAvoy, Paul, Qawami, Bahman, Chang, Robert C.
• Granted Patent: US 7,853,772 B2
• Time in Patent Office: Days
• US Class Current: 711/173
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

A method for re-allocating memory partition space is provided. The method comprises determining when a first memory partition is full or has reached a threshold value, determining that a second memory partition has unused storage space that can be allocated to the first memory partition, and assigning the unused storage space from the second memory partition to the first memory partition. A memory controller embedded within the mass storage device and having an interface to an external host assigns the unused storage space from the second memory partition to the first memory partition.

Claims

1-20. -20. (canceled)

21. A method for dynamically re-allocating data storage space in a mass storage device, the method comprising:

in a controller embedded within the mass storage device that has a memory space divided into partitions, which partitions include at least a first memory partition and a second memory partition, performing the steps of;

determining when the first memory partition is fall or has reached a threshold value;

determining that the second memory partition has unused storage space that can be allocated to the first memory partition that is fall or has reached a threshold value; and

assigning the unused storage space from the second memory partition to the first memory partition.

22. The method of claim 21, wherein the mass storage device includes re-programmable non-volatile memory cells, the memory cells being arranged in a plurality of blocks of memory cells that are erasable together and that are connected together in a plurality of series strings to define rows of memory cells for storing data.

23. The method of claim 21, wherein, when the mass storage device is connected via an interface to an external host, the method further comprises the steps, performed in the memory controller, of:

receiving data via the interface from the external host; and

reallocating the unused storage space from the second memory partition to the first memory partition using a mapping table that has a virtual block address for each of the first memory partition and the second memory partition, wherein the storage space reallocated from the second partition to the first partition appears contiguous to the external host.

24. The method of claim 21, wherein each of the first memory partition and the second memory partition includes storage space for storing a File Allocation Table (“

FAT”

), wherein the FAT is expanded or shrunk based on whether data space is being added to or taken away from a partition.

25. The method of claim 24, wherein the FAT for the first memory partition and the second memory partition is large enough to accommodate FAT entries for the entire mass storage device.

26. The method of claim 24, wherein entries in the FAT for the first memory partition and the second memory partition are adjusted when the unused storage space is re-allocated.

27. The method of claim 23, wherein when the mass storage device is initialized, the virtual address and a corresponding real logical address are the same for the first memory partition and the second memory partition.

28. The method of claim 21, wherein a file name entry in a directory is adjusted when the unused storage space is allocated from the second memory partition to the first memory partition.

29. The method of claim 21, wherein the mass storage device is one of a flash device and a magnetic hard disk.

30. The method of claim 21, wherein the controller re-allocates the unused storage space after receiving a command from an external host, and wherein the storage space assigned from the second partition to the first partition appears contiguous to the external host.

31. A method comprising:

in a memory controller embedded within a mass storage device that includes non-volatile memory cells, the mass storage device including a first memory partition and a second memory partition, performing the steps of;

when the mass storage device is connected via a logical interface to an external host, receiving data via the logical interface from the external host; and

re-allocating memory storage space from the first memory partition to the second memory partition by using a mapping table, wherein the mapping table includes a logical block address and a virtual block address for each of the first memory partition and the second memory partition, and wherein the memory storage space re-allocated from the first memory partition to the second memory partition appears contiguous to the external host.

32. The method of claim 31, wherein the external host comprises one of a computer, a telephone, a personal digital assistant (PDA), a digital still camera, a digital movie camera, and a portable audio player.

33. The method of claim 31, wherein the mass storage device is a flash memory device.

34. The method of claim 33, wherein the flash memory device includes one of a CompactFlash (CF) card, a MultiMediaCard (MMC) card, a Secure Digital (SD) card, a miniSD card, a Memory Stick card, and a TransFlash card.

35. The method of claim 31, wherein the logical interface comprises a universal serial bus (USB) interface.

36. The method of claim 31, wherein the virtual block address and the logical block address of the first memory partition are the same before the memory storage space is re-allocated from the first memory partition to the second memory partition, and the virtual block address and the logical block address of the first memory partition are different after the memory storage space is re-allocated from the first memory partition to the second memory partition.

37. The method of claim 36, wherein the first memory partition includes a first set of non-volatile memory cells, and the second memory partition includes a second set of non-volatile memory cells.

38. A flash memory device, comprising:

a first memory partition including a first set of non-volatile memory cells;

a second memory partition including a second set of non-volatile memory cells;

a mapping table including a logical block address and a virtual block address for each of the first memory partition and the second memory partition;

an interface adapted to connect to a host device and, when connected to the host device, to receive data from the host device; and

a memory controller;

wherein the memory controller is adapted to re-allocate memory storage space from the first memory partition to the second memory partition using the mapping table, wherein the memory storage space re-allocated from the first memory partition to the second memory partition appears contiguous to the host device; and

wherein the virtual block address and the logical block address of the first memory partition are the same before the memory storage space is re-allocated from the first memory partition to the second memory partition, and the virtual block address and the logical block address of the first memory partition are different after the memory storage space is re-allocated from the first memory partition to the second memory partition.

39. The flash memory device of claim 38, wherein the flash memory device includes one of a CompactFlash (CF) card, a MultiMediaCard (MMC) card, a Secure Digital (SD) card, a miniSD card, a Memory Stick card, and a TransFlash card.

40. The flash memory device of claim 38, wherein a file name entry in a directory is adjusted when the memory storage space is re-allocated from the first memory partition to the second memory partition.