Method for Providing Access to Data Items from a Distributed Storage System
First Claim
1. A method for providing access to data items from a distributed storage system having multiple storage nodes connected via a data communications network, each data item being replicated across a plurality of the storage nodes, the method comprising:
- receiving a request to retrieve the data item at a given node;
selecting, according to at least one detected characteristic of system status of the distributed storage system, a first or second reading mode to use in the retrieval of the data item, the first reading mode comprising attempting to read the data item from a set of storage nodes to check for data item consistency across at least a quorum of the set of storage nodes, the second reading mode comprising reading the data item from at least one of the storage nodes, said selecting the first or second reading mode comprising;
selecting the first reading mode when the detected characteristic of system status indicates a lower likelihood of data item consistency, andselecting the second reading mode when the detected characteristic of system status indicates a higher likelihood of data item consistency;
reading the data item from the distributed storage system using the selected reading mode; and
transmitting the data item, read by the selected reading mode, in response to the request to retrieve the data item.
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Accused Products
Abstract
A method for providing access to data items from a distributed storage system is provided. Each data item is replicated across a plurality of storage nodes. Data items are read from the distributed storage system by selecting between a first reading mode, comprising attempting to read the data item from a set of the storage nodes to check for data item consistency across at least a quorum of the set of nodes, and a second reading mode, comprising reading the data item from at least one of the storage nodes. The reading mode is selected according to at least one detected characteristic of system status of the distributed storage system. The second reading mode is selected when the detected characteristic indicates a higher likelihood of data item consistency, and the first reading mode is selected when the detected characteristic indicates a lower likelihood of data item consistency.
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Citations
17 Claims
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1. A method for providing access to data items from a distributed storage system having multiple storage nodes connected via a data communications network, each data item being replicated across a plurality of the storage nodes, the method comprising:
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receiving a request to retrieve the data item at a given node; selecting, according to at least one detected characteristic of system status of the distributed storage system, a first or second reading mode to use in the retrieval of the data item, the first reading mode comprising attempting to read the data item from a set of storage nodes to check for data item consistency across at least a quorum of the set of storage nodes, the second reading mode comprising reading the data item from at least one of the storage nodes, said selecting the first or second reading mode comprising; selecting the first reading mode when the detected characteristic of system status indicates a lower likelihood of data item consistency, and selecting the second reading mode when the detected characteristic of system status indicates a higher likelihood of data item consistency; reading the data item from the distributed storage system using the selected reading mode; and transmitting the data item, read by the selected reading mode, in response to the request to retrieve the data item. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for providing backup access to data items from a storage node of a distributed storage system having multiple storage nodes connected via a data communications network, each data item being replicated across a plurality of the storage nodes, the method comprising:
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detecting that the storage node has been disconnected from other storage nodes in a set of storage nodes across which data items have been replicated; querying one or more members of the set of storage nodes to identify a current leader node which is responsible for coordinating updates to the set of storage nodes; determining one or more data items in relation to which the storage node has missed an update to the set of storage nodes; and in response to said determining, querying one or more of the set of storage nodes to update a locally-stored data item to ensure consistency of the locally-stored data item with at least a quorum of the set of storage nodes. - View Dependent Claims (15)
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16. A method for providing backup access to data items from a storage node of a distributed storage system having multiple storage nodes connected via a data communications network, each data item being replicated across a plurality of the storage nodes, the method comprising:
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detecting that the storage node has failed and restarted; querying one or more members of a set of storage nodes to identify a current leader node which is responsible for coordinating updates to the set of storage nodes; determining an identifier of a point in a sequence of distributed storage system actions being coordinated by the current leader node, and participating in read and/or write actions instructed by the leader node which are beyond the point in the sequence.
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17. A computer program product comprising a non-transitory computer-readable storage medium having computer readable instructions stored thereon, the computer-readable instructions being executable by a computerized device to cause the computerized device to perform a method for providing access to data items from a distributed storage system having multiple storage nodes connected via a data communications network, each data item being replicated across a plurality of the storage nodes, the method comprising:
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receiving a request to retrieve the data item at a given node; selecting, according to at least one detected characteristic of system status of the distributed storage system, a first or second reading mode to use in the retrieval of the data item, the first reading mode including attempting to read the data item from a set of storage nodes to check for data item consistency across at least a quorum of the set of storage nodes, the second reading mode including reading the data item from at least one of the storage nodes, said selecting the first or second reading mode including; selecting the first reading mode when the detected characteristic of system status indicates a lower likelihood of data item consistency, and selecting the second reading mode when the detected characteristic of system status indicates a higher likelihood of data item consistency; reading the data item from the distributed storage system using the selected reading mode; and transmitting the data item, read by the selected reading mode, in response to the request to retrieve the data item.
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Specification