Leveraging Portable System Power to Enhance Memory Management and Enable Application Level Features

• US 20090089481A1
• Filed: 09/27/2007
• Published: 04/02/2009
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Parikh, Dhaval, Nagabhirava, Rajeev, Kapoor, Arjun
• Granted Patent: US 9,607,664 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 1/3275 Power saving in memory, e.g. RAM, cache
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/7203 Temporary buffering, e.g. using volatile buffer or dedicated buffer blocks
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0634 by changing the state or mode of one or more devices
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/225 Preventing erasure, programming or reading when power supply voltages are outside the required ranges
• CPC Class Codes: G11C 5/14 Power supply arrangements , e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels

Abstract

A memory device and techniques for its operation are presented. After operating on power received from a host, the memory device determines that it is no longer receiving host power and, in response, activates a power source on the memory device itself. Using this reserve power, the memory device can then perform data management operations. The techniques can also be applied to a digital appliance having a non-volatile memory. The memory device or digital appliance can prioritize its memory management operation during the host/user operating window based on the ability to perform these operations outside of the host/user operating window. Additionally, in a data write operations, where the memory device receives data from a host, stores the data in volatile memory, and then writes the data into the non-volatile memory, the memory device sends the host an acknowledgment of the data having been written into the non-volatile memory after it has been store in the volatile memory, but before the write into the non-volatile memory is complete.

Claims

1. A method of operating a memory device having a non-volatile memory for use with a host, the method comprising:

operating the memory device while connected to a host to receive and operate on power therefrom;

determining that the memory device is no longer receiving host power;

in response to determining that the memory device is no longer receiving host power, activating a reserve power source on the memory device; and

performing a data management operation on data stored in the non-volatile memory using the reserve power source.

2. The method of claim 1, wherein said data management operation includes prioritizing a plurality of operations and performing said operations according to said prioritization.

3. The method of claim 1, wherein said data management operation includes temporarily storing data content from the non-volatile memory in a volatile memory.

4. The method of claim 1, wherein said data management operation includes an application level operation.

5. The method of claim 1, wherein the non-volatile memory device includes a first plurality of non-volatile memory cells that can store data in a first data storage format having a first number of states and a second plurality of non-volatile memory cells that can store data in a second data storage format having a second number of states, wherein said second number of states is different than the first number of states, wherein said data management operation comprises:

rewriting host data stored in the first data storage format in memory cells of the first plurality into memory cells of the second plurality in the second data storage format.

6. A memory device comprising:

an interface for connection with a host to receive power therefrom;

a reserve power source;

a non-volatile memory; and

control circuitry connectable to the interface, the non-volatile memory, and reserve power source to control the transfer of data between the host and the non-volatile memory and manage the storage of data on the on the non-volatile memory using power received from the host,

wherein, in response to determining that the memory device is no longer receiving host power, the control circuitry can activate the reserve power source and perform data management operations on data stored in the non-volatile memory using the reserve power source.

7. The memory device of claim 6, wherein the control circuitry can prioritize a plurality of management operations and perform said plurality of operations according to said prioritization using the reserve power source.

8. The memory device of claim 6, further comprising:

a volatile memory, wherein said data management operations include temporarily storing data content from the non-volatile memory in the volatile memory.

9. The memory device of claim 6, wherein said data management operations include an application level operation.

10. The memory device of claim 6, wherein the non-volatile memory device includes a first plurality of non-volatile memory cells that can store data in a first data storage format having a first number of states and a second plurality of non-volatile memory cells that can store data in a second data storage format having a second number of states, wherein said second number of states is different than the first number of states, wherein said data management operations include rewriting host data stored in the first data storage format in memory cells of the first plurality into memory cells of the second plurality in the second data storage format.

11. A method of operating a digital appliance having a non-volatile memory for storing user data, the method comprising:

operating the digital appliance in a first mode wherein a user thereof can access user data stored in the non-volatile memory;

powering down the digital appliance;

in response to said powering down, operating the digital appliance in a second mode wherein a user thereof cannot access user data stored in the non-volatile memory; and

performing a data management operation on data stored in the non-volatile memory while operating in the second mode.

12. The method of claim 11, wherein said powering down is in response to a user input.

13. The method of claim 11, wherein said data management operation includes prioritizing a plurality of operations and performing said operations according to said prioritization.

14. The method of claim 11, wherein said data management operation includes temporarily storing data content from the non-volatile memory in a volatile memory.

15. The method of claim 11, wherein said data management operation includes an application level operation.

16. A method of operating a device having a non-volatile memory for storing user data, the device having a first operating mode for user operations, in which a user can access user data stored in the non-volatile memory and the device can perform data management operations, and a second operating mode, wherein the device is powered down as seen by the user and wherein the user cannot access user data stored in the non-volatile memory, the method comprising:

prioritizing, while operating in the first mode, management operations to perform on data stored in the non-volatile memory, the prioritizing including scheduling one or more of said data operations to be performed while the device is in the second operating mode;

powering down of the device; and

performing one or more of the scheduled data operations during the second operating mode.

17. The method of claim 16, wherein said device is a non-volatile memory device for use with a host to store data therefrom, wherein during the first mode the memory device is connected to a host to receive and operate on power therefrom and during the second mode the memory device uses a reserve power source on the memory device.

18. The method of claim 16, wherein said device is a digital appliance including the non-volatile memory for storing user data.

19. The method of claim 16, wherein during the second mode, the device powers down one or more components not required to perform the scheduled data operations during the second operating mode.

20. The method of claim 16, wherein in response to a user input, the device returns to the first mode.

21. A device comprising:

a non-volatile memory for storing user data;

a power source; and

control circuitry connectable to non-volatile memory and the power source to manage the storage of data on the on the non-volatile memory using power from the power source, wherein, the control circuitry can manage the non-volatile memory in a first operating mode for user operations, in which a user can access user data stored in the non-volatile memory and the device can perform data management operations, and a second operating mode, wherein the device is powered down as seen by the user and wherein the user cannot access user data stored in the non-volatile memory, and

wherein, while operating in the first mode, the control circuitry prioritizes management operations to perform on data stored in the non-volatile memory, the prioritizing including scheduling one or more of said data operations to be performed while the device is in the second operating mode.

22. The device of claim 21, wherein said device is a non-volatile memory device for use with a host to store data therefrom and said power source is a reserve power source on the memory device, wherein during the first mode the memory device is connected to a host to receive and operate on power therefrom and during the second mode the memory device uses the reserve power source.

23. The device of claim 21, wherein said device is a digital appliance including the non-volatile memory for storing user data.

24. The device of claim 21, wherein during the second mode, the device powers down one or more components not required to perform the scheduled data operations during the second operating mode.

25. The device of claim 21, wherein in response to a user input, the device returns to the first mode.

26. A method of operating a non-volatile memory device for use with a host, the memory device including a non-volatile memory for the storage of host data and a volatile memory for temporary data storage, wherein the memory device is detachably connectable to a host to receive and operate on power therefrom, the method comprising:

receiving data from a host;

storing said data in the volatile memory;

subsequently writing said data from the volatile memory into the non-volatile memory; and

subsequent to storing said data in the volatile memory and prior to completing the writing of said data into the non-volatile memory, sending an acknowledgement to the host that said data has been written into the non-volatile memory.

27. The method of claim 26, wherein the memory system further includes a reserve power source, the method further comprising:

subsequent to sending said acknowledgement and prior to completing writing said data into the non-volatile memory, activating the reserve power source; and

completing writing said data into the non-volatile memory using the reserve power source.

28. The method of claim 27, wherein the memory system activates the reserve power source in response to determining a loss of host power.

29. A non-volatile memory device for use with a host, wherein the memory device is detachably connectable to a host to receive and operate on power therefrom, the memory device including:

a non-volatile memory for the storage of host data;

control circuitry to manage the transfer of data between the non-volatile memory and a host to which the memory device is connected; and

a volatile memory for temporary data storage, wherein in a write operation of host data, the host data is received from the host, stored in the volatile memory, and then programmed into the non-volatile memory, and

wherein the control circuitry sends an acknowledgement to the host that said data has been written into the non-volatile memory subsequent to storing said data in the volatile memory and prior to completing the programming of said data into the non-volatile memory.

30. The memory of claim 29, further including:

a reserve power source, wherein, in response to determining a loss of host power subsequent to sending said acknowledgement and prior to completing writing said data into the non-volatile memory, the control circuitry activates the reserve power source and completes programming the host data into the non-volatile memory using the reserve power source.