Invention Grant
- Patent Title: Online metadata backup consistency check
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Application No.: US15656168Application Date: 2017-07-21
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Publication No.: US10705918B1Publication Date: 2020-07-07
- Inventor: Ying Hu , Xiangping Chen
- Applicant: EMC IP Holding Company LLC
- Applicant Address: US MA Hopkinton
- Assignee: EMC IP Holding Company LLC
- Current Assignee: EMC IP Holding Company LLC
- Current Assignee Address: US MA Hopkinton
- Agency: Daly Crowley Mofford & Durkee, LLP
- Main IPC: G06F11/14
- IPC: G06F11/14 ; G06F16/215

Abstract:
A storage system comprises a storage device and metadata journal comprising metadata configured to store information associated with changes to information stored on the storage device. Dirty tree (DT) metadata pages, each corresponding to information written to the storage device from the metadata journal, are stored on the storage device. DT pages are read and scanned to detect if any DT metadata page comprises an entry having an invalid snap group ID associated with a given offset. For each detected DT metadata page comprising a respective invalid snap group ID, a corresponding fake journal entry is created in metadata journal and configured to point to the respective DT metadata page comprising the invalid snap group ID and given offset. The fake journal entry is configured so that, when the metadata journal is destaged to the storage device, the invalid snap group ID is reset to nonexistent.
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