System and method for increasing capacity, performance, and flexibility of flash storage

• US 8,751,732 B2
• Filed: 09/14/2012
• Issued: 06/10/2014
• Est. Priority Date: 10/05/2006
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Danilak, Radoslav, Smith, Michael J. S., Rajan, Suresh
• Primary Examiner(s): PEUGH, BRIAN R
• Application Number:
  US13/620,424
• Publication Number:
  US 20130132645A1
• Time in Patent Office: 634 Days
• Field of Search: None
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 13/385 for adaptation of a particular data processing system to different peripheral devices
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

In one embodiment, an interface circuit is configured to couple to one or more flash memory devices and is further configured to couple to a host system. The interface circuit is configured to present at least one virtual flash memory device to the host system, wherein the interface circuit is configured to implement the virtual flash memory device using the one or more flash memory devices to which the interface circuit is coupled.

Claims

1. A sub-system comprising:

a first number of physical flash memory devices;

an interface circuit coupled to the first number of physical flash memory devices, the interface circuit comprising;

logic configured to;

detect, from one or more of the first number of physical flash memory devices, a physical configuration including a first capacity; and

store a virtual configuration for a second number of virtual flash memory devices, wherein the virtual configuration defines one or more desired attributes that differ from corresponding attributes of the first number of physical flash memory devices;

a host interface configured to be coupled to a host system, the host system configured to present to the host system the second number of virtual flash memory devices having the one or more desired attributes defined in the virtual configuration; and

a translation unit configured to translate between a protocol of the second number of virtual flash memory devices and a protocol of the first number of physical flash memory devices based on differences between the virtual configuration and the detected physical configuration.

2. The sub-system of claim 1, wherein the one or more desired attributes include one or more of a page size, a bus width, a block size, a redundant storage area, a plane size, an access time with flash memory devices, a cache size, an interleave configuration, an auto configuration, or an open NAND flash interface (ONFI).

3. The sub-system of claim 1, wherein the translation unit is further configured to perform a test to verify that a total capacity of the second number of virtual flash memory devices is equal to or less than a total capacity of the first number of physical flash memory devices.

4. The sub-system of claim 1, wherein the physical configuration includes a first data width organization, wherein the virtual configuration includes a different, second data width organization, and wherein the translation unit is further configured to select a portion of data provided by the physical flash memory devices to satisfy the second data width organization of the virtual flash memory devices.

5. The sub-system of claim 1,

wherein the physical flash memory devices are multi-level cell (MLC) flash devices,

wherein the host interface is configured to present the virtual flash memory devices as single-level cell (SLC) flash devices, and

wherein the translation unit is further configured to translate between SLC protocols and MLC protocols.

6. The sub-system of claim 1,

wherein the physical flash memory devices are NAND flash devices,

wherein the host interface is configured to present the virtual flash memory devices as NOR flash devices, and

wherein the translation unit is further configured to translate between NAND protocols and NOR protocols.

7. The sub-system of claim 1, wherein the interface circuit further comprises:

a prefetch circuit configured to;

determine that a read command to read from a particular virtual memory block of the virtual flash memory devices is likely to be received from the host system;

in response to determining that the read command is likely to be received, identify one or more particular physical memory blocks of the physical flash memory devices that correspond to the particular virtual memory block;

issue one or more corresponding read commands to prefetch data in the one or more particular physical memory blocks before receiving the read command from the host system; and

store the prefetched data.

8. The sub-system of claim 1, wherein the host interface is further configured to receive the read command from the host system, and the prefetch circuit is configured to provide the prefetched data to the host system in response to receiving the read command without issuing a read command to the physical flash memory devices.

9. The sub-system of claim 1, wherein the interface circuit further comprises:

a read-only memory (ROM) storing fixed configuration information associated with the first number of physical memory devices.

10. The sub-system of claim 9, wherein the logic is further configured to access the fixed configuration information stored at the ROM, and to determine the virtual configuration based on the fixed configuration information and the detected physical configuration.

11. An interface circuit coupled to a first number of physical flash memory devices, the interface circuit comprising:

logic configured to;

detect, from one or more of the first number of physical flash memory devices, a physical configuration including a first capacity; and

store a virtual configuration for a second number of virtual flash memory devices, wherein the virtual configuration defines one or more desired attributes that differ from corresponding attributes of the first number of physical flash memory devices;

a host interface configured to be coupled to a host system, the host system configured to present to the host system the second number of virtual flash memory devices having the one or more desired attributes defined in the virtual configuration; and

a translation unit configured to translate between a protocol of the second number of virtual flash memory devices and a protocol of the first number of physical flash memory devices based on differences between the virtual configuration and the detected physical configuration.

12. The interface circuit of claim 11, wherein the one or more desired attributes include one or more of a page size, a bus width, a block size, a redundant storage area, a plane size, an access time with flash memory devices, a cache size, an interleave configuration, an auto configuration, or an open NAND flash interface (ONFI).

13. The interface circuit of claim 11, wherein the translation unit is further configured to perform a test to verify that a total capacity of the second number of virtual flash memory devices is equal to or less than a total capacity of the first number of physical flash memory devices.

14. The interface circuit of claim 11, wherein the physical configuration includes a first data width organization, wherein the virtual configuration includes a different, second data width organization, and wherein the translation unit is further configured to select a portion of data provided by the physical flash memory devices to satisfy the second data width organization of the virtual flash memory devices.

15. The interface circuit of claim 11, further comprising:

a prefetch circuit configured to;

determine that a read command to read from a particular virtual memory block of the virtual flash memory devices is likely to be received from the host system;

in response to determining that the read command is likely to be received, identify one or more particular physical memory blocks of the physical flash memory devices that correspond to the particular virtual memory block;

issue one or more corresponding read commands to prefetch data in the one or more particular physical memory blocks before receiving the read command from the host system; and

store the prefetched data.

16. The interface circuit of claim 11, further comprising:

a read-only memory (ROM) storing fixed configuration information associated with the first number of physical memory devices.

17. The interface circuit of claim 16, wherein the logic is further configured to access the fixed configuration information stored at the ROM, and to determine the virtual configuration based on the fixed configuration information and the detected physical configuration.

18. The interface circuit of claim 11, wherein the physical configuration includes a first data width organization, wherein the virtual configuration includes a different, second data width organization, and wherein the translation unit is further configured to select a portion of data provided by the physical flash memory devices to satisfy the second data width organization of the virtual flash memory devices.

19. The interface circuit of claim 11,

wherein the physical flash memory devices are multi-level cell (MLC) flash devices,

wherein the host interface is configured to present the virtual flash memory devices as single-level cell (SLC) flash devices, and

wherein the translation unit is further configured to translate between SLC protocols and MLC protocols.

20. The interface circuit of claim 11,

wherein the physical flash memory devices are NAND flash devices,

wherein the host interface is configured to present the virtual flash memory devices as NOR flash devices, and

wherein the translation unit is further configured to translate between NAND protocols and NOR protocols.