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US 6,192,460 B1Granted
Method and apparatus for accessing data in a shadow set after a failed data operation
AssigneeCompaq Computer Corporation
InventorsWilliam Lyle Goleman, Scott Howard Davis, David William Thiel
Life of this patent
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Abstract
Disclosed is a method and apparatus for accessing data in a computer system after a failed data operation in which I/O process state information is unknown. The failed data operation may cause data inconsistency among multiple devices associated with a shadow set for storing data. The disclosed system includes techniques for allowing continued data accesses while simultaneously re-establishing data consistency among members of the shadow set.
Claims13
A method of accessing data in a computer system from a shadow set after a failed data operation, the method comprising the steps of:
- detecting said failed data operation in the computer system;
- maintaining a host transaction list by recording data operations in said host transaction list indicating that, upon completion of each of said data operations, a storage area of the shadow set associated with each of said data operations contains only consistent data;
- and
- performing another data operation subsequent to the failed data operation and determining directly from an entry in said host transaction list whether a storage area associated with said another data operation contains consistent data, wherein said determining is accomplished without performing a read operation on a member of the shadow set.
1 more element
Dependencies are inferred from the claim text.