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Robert Haas, Nikolas Ioannou, Ioannis Koltsidas, Roman Pletka, Andrew Walls
Two-level Hierarchical Log Structured Array Architecture with Minimized Write Amplification
US 9,619,158
Filing Date: 2014-12-17
Issue Date: 2017-04-11

A mechanism is provided for coordinated garbage collection in an array controller of a two-level hierarchical log structured array architecture for a non-volatile memory array. The two-level hierarchical log structured array (LSA) architecture comprises an array-level LSA in the array controller and a node-level LSA in each node of the non-volatile memory array. The array controller writes logical pages of data to containers in memory of the array-level storage controller at node logical block addresses in an array-level LSA. The array-level LSA maps the host logical block addresses to node logical block addresses in a node-level LSA in a plurality of nodes. Responsive to initiating array-level garbage collection in the array controller, the mechanism identifies a first container to reclaim according to a predetermined garbage collection policy. Responsive to determining the first container has at least a first valid logical page of data, the mechanism moves the first valid logical page of data to a location assigned to the same node in a target container in the memory of the array-level storage controller, remaps the first valid logical page of data in a corresponding node, and reclaims the first container.

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