Failover and failback of write cache data in dual active controllers
AssigneeSeagate Technology LLC
InventorsClark E. Lubbers, Michael D. Walker, Susan G. Elkington
Life of this patent
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Abstract
A data storage system is provided with a pair of controllers and circuitry configured for failing back from a single active write back mode to a dual active write back mode by copying cached data directly from a cache of a survivor controller of the pair of controllers to a cache of the other controller. A method is provided for failing over from a dual active mode of first and second controllers to a single active mode of the first controller by relying on previously mirrored cache data by the second controller; reinitializing the second controller; and failing back to the dual active mode by copying cached data directly from the first controller to the second controller.
Claims19
A data storage system comprising a pair of controllers processing input/output commands directed to a storage space and circuitry configured for failing back from a failure of one of the controllers by copying cached data directly from a cache of a survivor controller of the pair of controllers to a cache of the other controller without the survivor controller flushing copied cached data with respect to the storage space, at a time before the controllers resume processing input/output commands in a dual active mode.
A method for processing input/output commands with respect to a storage space comprising:
- failing over from a dual active mode of first and second controllers to a single active mode of the first controller by relying on previously mirrored cache data from the second controller;
- reinitializing the second controller;
- and
- failing back to the dual active mode by copying cached data directly from the first controller to the second controller without the first controller flushing copied cached data with respect to the storage space, at a time before the controllers resume processing the input/output commands in a dual active mode.
Dependencies are inferred from the claim text.