Method and system for synchronizing volumes in a continuous data protection system
First Claim
1. A method for synchronizing a secondary volume with a primary volume in a continuous data protection system, comprising the steps of:
- scanning a region of the primary volume;
comparing the scanned region with a corresponding region of the secondary volume;
storing an identification of the scanned region in a compare delta map when the comparing step results in a discrepancy between the scanned region and the corresponding region;
copying data from the primary volume to the secondary volume, using the compare delta map as a guide to locate the data to copy; and
revising the compare delta map by removing any changes made to the primary volume during a scan interval, which is the period of time required to scan the primary volume, the revising step being performed before the copying step.
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Abstract
A method for synchronizing a secondary volume with a primary volume in a continuous data protection system begins by scanning a region of the primary volume, which is then compared with a corresponding region of the secondary volume. An identification of the scanned region is stored in a compare delta map when the comparison results in a discrepancy between the scanned region and the corresponding region. Data is copied from the primary volume to the secondary volume, using the compare delta map as a guide to locate the data to copy. If the data protection system has failed just prior to the restore process being initiated, it is termed a re-baseline, and the entire primary volume is scanned. If the data protection system is active prior to the restore process being initiated, it is termed a re-synchronization, and is optimized by scanning only select regions of the primary volume.
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Citations
10 Claims
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1. A method for synchronizing a secondary volume with a primary volume in a continuous data protection system, comprising the steps of:
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scanning a region of the primary volume; comparing the scanned region with a corresponding region of the secondary volume; storing an identification of the scanned region in a compare delta map when the comparing step results in a discrepancy between the scanned region and the corresponding region; copying data from the primary volume to the secondary volume, using the compare delta map as a guide to locate the data to copy; and revising the compare delta map by removing any changes made to the primary volume during a scan interval, which is the period of time required to scan the primary volume, the revising step being performed before the copying step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification