SAND TIMER ALGORITHM FOR TRACKING IN-FLIGHT DATA STORAGE REQUESTS FOR DATA REPLICATION
First Claim
1. A method for use in a first storage subsystem having a management node and a plurality of storage nodes, each of the storage nodes having a respective pair of tracking tables for recording in-flight data storage requests, the tracking tables in each pair having different respective designations, the tracking tables in each pair alternating between a drain table designation and an active table designation, the method comprising:
- generating a first snapshot of the first storage subsystem;
detecting, by the management node, that all in-flight data storage requests recorded in the drain tables of the storage nodes have been completed, the in-flight data storage requests recorded in the drain tables of the storage nodes being replicated in a second storage subsystem;
causing, by the management node, each of the plurality of storage nodes to flip the respective designations of the tracking tables in the node'"'"'s respective pair of tracking tables; and
transmitting, from the management node to the second storage subsystem, an instruction which when received by the second storage subsystem causes the second storage subsystem to generate a second snapshot of the second storage subsystem, the instruction being transmitted after the first snapshot is generated and all in-flight data storage requests recorded in the drain tables of the storage nodes have been completed.
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Accused Products
Abstract
A method is disclosed comprising: generating a first snapshot of a first storage subsystem; detecting, by a management node, that all in-flight data storage requests recorded in drain tables of storage nodes in the first storage subsystem have been completed, the in-flight data storage requests recorded in the drain tables of the storage nodes being replicated in a second storage subsystem; causing, by the management node, each of the storage nodes to flip the respective designations of the tracking tables in the node'"'"'s respective pair of tracking tables; and transmitting, from the management node to the second storage subsystem, an instruction which when received by the second storage subsystem causes the second storage subsystem to generate a second snapshot of the second storage subsystem.
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Citations
20 Claims
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1. A method for use in a first storage subsystem having a management node and a plurality of storage nodes, each of the storage nodes having a respective pair of tracking tables for recording in-flight data storage requests, the tracking tables in each pair having different respective designations, the tracking tables in each pair alternating between a drain table designation and an active table designation, the method comprising:
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generating a first snapshot of the first storage subsystem; detecting, by the management node, that all in-flight data storage requests recorded in the drain tables of the storage nodes have been completed, the in-flight data storage requests recorded in the drain tables of the storage nodes being replicated in a second storage subsystem; causing, by the management node, each of the plurality of storage nodes to flip the respective designations of the tracking tables in the node'"'"'s respective pair of tracking tables; and transmitting, from the management node to the second storage subsystem, an instruction which when received by the second storage subsystem causes the second storage subsystem to generate a second snapshot of the second storage subsystem, the instruction being transmitted after the first snapshot is generated and all in-flight data storage requests recorded in the drain tables of the storage nodes have been completed. - View Dependent Claims (2, 3, 4, 5, 6)
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7. (canceled)
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8. An apparatus for use in a first storage subsystem having a plurality of storage nodes, each of the storage nodes having a respective pair of tracking tables for recording in-flight data storage requests, the tracking tables in each pair having different respective designations, the tracking tables in each pair alternating between a drain table designation and an active table designation, the apparatus comprising:
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a memory; and at least one processor operatively coupled to the memory, the at least one processor being configured to; generate a first snapshot of the first storage subsystem; detect that all in-flight data storage requests recorded in the drain tables of the storage nodes have been completed, the in-flight data storage requests recorded in the drain tables of the storage nodes being replicated in a second storage subsystem; cause each of the plurality of storage nodes to flip the respective designations of the tracking tables in the node'"'"'s respective pair of tracking tables; and transmit, to the second storage subsystem, an instruction which when received by the second storage subsystem causes the second storage subsystem to generate a second snapshot of the second storage subsystem, the instruction being transmitted after the first snapshot is generated and all in-flight data storage requests recorded in the drain tables of the storage nodes have been completed. - View Dependent Claims (9, 10, 11, 12, 13)
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14. (canceled)
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15. A non-transitory computer-readable medium configured to store one or more processor-executable instructions which when executed by at least one processor cause the at least one processor to perform the operations of:
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identifying a plurality of storage nodes in a first storage subsystem, each of the storage nodes having a respective pair of tracking tables for recording in-flight data storage requests, the tracking tables in each pair having different respective designations, the tracking tables in each pair alternating between a drain table designation and an active table designation; generating a first snapshot of the first storage subsystem; detecting that all in-flight data storage requests recorded in drain tables of the storage nodes have been completed, the in-flight data storage requests recorded in the drain tables of the storage nodes being replicated in a second storage subsystem; causing each of the plurality of storage nodes to flip the respective designations of the tracking tables in the node'"'"'s respective pair of tracking tables; and transmitting to the second storage subsystem, an instruction which when received by the second storage subsystem causes the second storage subsystem to generate a second snapshot of the second storage subsystem, the instruction being transmitted after the first snapshot is generated and all in-flight data storage requests recorded in the drain tables of the storage nodes have been completed. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification