Accelerated recovery in data replication environments
First Claim
1. A method for accelerating recovery in a data replication environment, the method comprising:
- suspending, in response to an outage at a primary volume, I/O from a host system to the primary volume;
maintaining, for a secondary volume, a secondary out-of-sync bitmap indicating which storage elements on the secondary volume are not synchronized with storage elements on the primary volume;
maintaining, for the primary volume, a tracking bitmap indicating which storage elements on the primary volume need to be updated with data from the secondary volume;
initially synchronizing the tracking bitmap with the secondary out-of-sync bitmap;
after the tracking bitmap is initially synchronized with the secondary out-of-sync bitmap, but before the storage elements on the primary volume are fully synchronized with the storage elements on the secondary volume, resuming I/O from the host system to the primary volume; and
upon receiving a write from the secondary volume to a storage element on the primary volume, resetting the corresponding bit in the tracking bitmap.
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Abstract
A method for accelerating recovery in a data replication environment includes maintaining a secondary out-of-sync bitmap for a secondary volume. The secondary out-of-sync bitmap indicates which storage elements on the secondary volume are not synchronized with storage elements on a primary volume. The method further generates, for the primary volume, a tracking bitmap indicating which storage elements on the primary volume need to be updated with data from the secondary volume. This tracking bitmap is initialized with values from the secondary out-of-sync bitmap. Upon receiving a write from the secondary volume to a storage element on the primary volume, the method resets the corresponding bit in the tracking bitmap. Upon receiving a write from a host system to a storage element on the primary volume, the method also resets the corresponding bit in the tracking bitmap. A corresponding system and computer program product are also disclosed.
38 Citations
20 Claims
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1. A method for accelerating recovery in a data replication environment, the method comprising:
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suspending, in response to an outage at a primary volume, I/O from a host system to the primary volume; maintaining, for a secondary volume, a secondary out-of-sync bitmap indicating which storage elements on the secondary volume are not synchronized with storage elements on the primary volume; maintaining, for the primary volume, a tracking bitmap indicating which storage elements on the primary volume need to be updated with data from the secondary volume; initially synchronizing the tracking bitmap with the secondary out-of-sync bitmap; after the tracking bitmap is initially synchronized with the secondary out-of-sync bitmap, but before the storage elements on the primary volume are fully synchronized with the storage elements on the secondary volume, resuming I/O from the host system to the primary volume; and upon receiving a write from the secondary volume to a storage element on the primary volume, resetting the corresponding bit in the tracking bitmap. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computer program product for accelerating recovery in a data replication environment, the computer program product comprising a non-transitory computer-readable storage medium having computer-usable program code embodied therein, the computer-usable program code comprising:
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computer-usable program code to suspend, in response to an outage at a primary volume, I/O from a host system to the primary volume; computer-usable program code to maintain, for a secondary volume, a secondary out-of-sync bitmap indicating which storage elements on the secondary volume are not synchronized with storage elements on a primary volume; computer-usable program code to generate, for the primary volume, a tracking bitmap indicating which storage elements, on the primary volume, need to be updated with data from the secondary volume; computer-usable program code to initially synchronize the tracking bitmap with the secondary out-of-sync bitmap; computer-usable program code to, after the tracking bitmap is initially synchronized with the secondary out-of-sync bitmap, but before the storage elements on the primary volume are fully synchronized with the storage elements on the secondary volume, resume I/O from the host system to the primary volume; and computer-usable program code to, upon receiving a write from the secondary volume to a storage element on the primary volume, reset the corresponding bit in the tracking bitmap. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for accelerating recovery in a data replication environment, the system comprising:
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at least one processor; at least one memory device coupled to the at least one processor and storing instructions for execution on the at least one processor, the instructions causing the at least one processor to; suspend, in response to an outage at a primary volume, I/O from a host system to the primary volume; maintain, for a secondary volume, a secondary out-of-sync bitmap indicating which storage elements on the secondary volume are not synchronized with storage elements on a primary volume; generate, for the primary volume, a tracking bitmap indicating which storage elements, on the primary volume, need to be updated with data from the secondary volume; initially synchronize the tracking bitmap with the secondary out-of-sync bitmap; after the tracking bitmap is initially synchronized with the secondary out-of-sync bitmap, but before the storage elements on the primary volume are fully synchronized with the storage elements on the secondary volume, resume I/O from the host system to the primary volume; and upon receiving a write from the secondary volume to a storage element on the primary volume, reset the corresponding bit in the tracking bitmap. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification