Method and apparatus for creating a virtual data copy
First Claim
1. A method comprising:
- copying data from a memory region of a first memory to a memory region of a second memory;
setting a first bit in memory that corresponds to the memory region of the second memory, wherein the first bit is set to indicate that the memory region of the second memory stores data copied from the memory region of first memory;
modifying data stored in the memory region of the second memory after data is copied from the memory region of the first memory to the memory region of the second memory;
setting a second bit in memory, wherein the second bit is set to indicate that the data stored in the memory region of the second memory has been modified since data stored in the memory region of the second memory was copied from the memory region of the first memory.
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Abstract
Disclosed is a method for creating a virtual copy of data stored in a first memory. The virtual copy of data stored in the first memory is created in a second memory in response to a request to create a copy of all data stored in the first memory. Creating the virtual copy includes, in one embodiment, creating first and second tables in memory each one of which comprises a plurality of multibit entries. Each entry of the first table corresponds to a respective memory region of the first memory. Each entry of the second table corresponds to a respective memory region of the second memory. Each first bit of the first table indicates whether the corresponding memory region of the first memory contains valid data. Each second bit of the first table indicates whether data in the corresponding memory region of the first memory has been modified since the first table was created. Each first bit of the second table indicates whether the corresponding memory region of the second memory contains data copied from the first memory. Each second bit of the second table indicates whether data in the corresponding memory region of the second memory has been modified since the second table was created. Additionally, using the present invention more than one virtual copy of data stored in the first memory can be created at a time. Further, using the present invention, a virtual copy of the virtual copy can be created.
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Citations
24 Claims
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1. A method comprising:
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copying data from a memory region of a first memory to a memory region of a second memory;
setting a first bit in memory that corresponds to the memory region of the second memory, wherein the first bit is set to indicate that the memory region of the second memory stores data copied from the memory region of first memory;
modifying data stored in the memory region of the second memory after data is copied from the memory region of the first memory to the memory region of the second memory;
setting a second bit in memory, wherein the second bit is set to indicate that the data stored in the memory region of the second memory has been modified since data stored in the memory region of the second memory was copied from the memory region of the first memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 22, 23, 24)
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9. A computer readable memory for storing instructions executable by a computer system, wherein the computer system performs a method in response to executing the instructions, the method comprising:
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creating a first virtual copy of data stored in a first memory, wherein the first virtual copy is created in a second memory;
creating a second virtual copy of data stored in the first memory, wherein the second virtual copy is created in a third memory, and wherein the second virtual copy is created after the creation of the first virtual copy.
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- 10. A computer readable memory for storing instructions executable by a computer system, wherein a method is performed in response to executing the instructions, the method comprising creating a virtual copy of data stored in a first memory, wherein the virtual copy of data stored in the first memory is created in a second memory in response to a request to create a copy of all data stored in the first memory.
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18. A system comprising:
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a computer system;
a first data storage system coupled to the computer system, wherein the first data storage system comprises a first memory;
a second data storage system coupled to the computer system, wherein the second data storage system comprises a second memory;
wherein the computer system comprises a processor for executing instructions and a memory that stores instructions executable by the processor to implement a method, the method comprising;
creating a virtual copy of data stored in the first memory, wherein the virtual copy of data stored in the first memory is created in the second memory in response to a request to create a copy of the data stored in the first memory.
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19. An apparatus comprising:
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a first memory;
a second memory coupled the first memory, wherein a total memory space of the second memory is equal to or greater than a total memory space of the first memory;
means for creating a virtual copy of data stored in the first memory, wherein the virtual copy of data stored in the first memory is created in the second memory in response to a request to create a copy of the data stored in the first memory.
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20. A system comprising:
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means for copying data from a memory region of a first memory to a memory region of a second memory;
means for setting a first bit in memory that corresponds to the memory region of the second memory, wherein the first bit is set to indicate that the memory region of the second memory stores data copied from the memory region of first memory;
means for modifying data stored in the memory region of the second memory after data is copied from the memory region of the first memory to the memory region of the second memory;
means for setting a second bit in memory, wherein the second bit is set to indicate that the data stored in the memory region of the second memory has been modified since data stored in the memory region of the second memory was copied from the memory region of the first memory. - View Dependent Claims (21)
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Specification