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US 8,942,072 B2Granted
Efficient access to storage devices with usage bitmaps
AssigneeMicrosoft Corporation
InventorsKaran Mehra, Surendra Verma, John R. Dietrick
Life of this patent
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AssigneeMicrosoft Corporation
InventorsKaran Mehra, Surendra Verma, John R. Dietrick
Estimating the term…
Upon receiving a request to allocate a storage region, a storage device may initialize the contents of the storage device to default values (e.g., zero) in order to avoid problems arising from unknown data stored in the locations of the storage region (e.g., upon writing a data set to a location involved in a mirroring relationship, uninitialized data in the corresponding mirror location may result in a mismatch that jeopardizes the written data). However, initializing the storage device may be time-consuming and inefficient. Instead, a usage bitmap may be generated that, for respective location sets of the storage region, indicates whether values exist in the location. A read request may be fulfilled by examining the usage bitmap to determine whether values exist in the specified location, and if not, the default value may be returned without accessing the storage device. Other efficiencies may also be achieved using the usage bitmap.
A method of presenting values of a storage set storing a usage bitmap, a journal storing values to be written to the storage set, and at least one storage region at a location in a location set, the method comprising:
A system for presenting values stored in location sets comprising at least two locations of a storage set, the system comprising:
A computer-readable memory device storing instructions that, when executed on a processor of a device, cause the device to present values of a storage set having at least one storage region respectively stored at a location in a location set;
Dependencies are inferred from the claim text.