Systems for Managing File Allocation Table Information

• US 20080082773A1
• Filed: 09/29/2006
• Published: 04/03/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Tomlin, Andrew, Gorobets, Sergey Anatolievich
• Granted Patent: US 7,681,008 B2
• Time in Patent Office: Days
• US Class Current: 711/170
• CPC Class Codes: G06F 12/023 Free address space management

Abstract

In a nonvolatile memory system, a host allocates clusters and records allocation information in a File Allocation Table that is stored in the nonvolatile memory. A controller separately allocates certain data and records allocation in a record in a volatile memory. File Allocation Table information provided to the host is modified according to the record in the volatile memory.

Claims

1. A nonvolatile memory system comprising:

a nonvolatile memory array that stores data from a host and stores a file system structure that indicates allocation of the data by the host to at least a first portion of a logical address space;

a controller that manages data in the nonvolatile memory array, the controller allocating at least a second portion of the logical address space without indicating the allocation of the second portion in the file system structure; and

a volatile memory that records allocation of the second portion of the logical address space by the controller.

2. The nonvolatile memory system of claim 1 wherein the nonvolatile memory array is not erasable.

3. The nonvolatile memory system of claim 1 wherein the volatile memory and the controller are formed on a common die.

4. The nonvolatile memory system of claim 1 wherein the second portion of the logical address space is allocated by the controller for data sent by the host to update data that was previously stored in the nonvolatile memory array.

5. The nonvolatile memory system of claim 1 further comprising an embedded application in the nonvolatile memory system, the second portion of the logical address space allocated by the controller for data stored by the embedded application.

6. The nonvolatile memory system of claim 1 further comprising an editor in the controller, the editor modifying the file system structure when it is read from the nonvolatile memory array before sending the modified file system structure to the host.

7. The nonvolatile memory system of claim 6 wherein the editor modifies the file system structure according to information recorded in the volatile memory.

8. The nonvolatile memory system of claim 1 wherein the nonvolatile memory system is embodied in a removable memory card.

9. The nonvolatile memory system of claim 1 wherein, in response to a host request for allocation information from the nonvolatile memory system for a logical address, the controller checks the volatile memory and, if the volatile memory show the logical address is not allocated, the controller returns an indication that the logical address is not allocated without reading allocation information from the nonvolatile memory array.

10. A nonvolatile memory system comprising:

a nonvolatile memory array that stores data from a host and stores a file system structure that indicates allocation of the data by the host; and

a memory controller that manages data in the nonvolatile memory array, the memory controller including an editor that modifies the file system structure from the nonvolatile memory array according to a record stored in a volatile memory, the memory controller sending the modified file system structure to the host in response to a host request.

11. The nonvolatile memory system of claim 10 wherein the record indicates allocation of logical space by the controller

12. The nonvolatile memory system of claim 10 wherein the nonvolatile memory array is not erasable.

13. The nonvolatile memory system of claim 10 wherein the nonvolatile system is in a removable memory card that interfaces with a host according to an interface.