Method for rebuilding meta-data in a data storage system and a data storage system
First Claim
1. A method for rebuilding meta-data in a storage system having storage devices in which segments of data are located, wherein data is written in segments to the storage devices from a plurality of flows of data and each segment of data also contains meta-data relating to that segment;
- the method comprising;
scanning the meta-data in each segment to identify the last segment written from each flow;
rebuilding the meta-data in the storage system using the meta-data in the segments excluding the meta-data for the segments identified as being the last segments written from each flow.
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Abstract
A method for rebuilding meta-data stored in a data storage system (104) having storage devices (106) in which segments of data are located; for example, a storage system in the form of a log structured array. Data is written in segments to the storage devices (106) from a plurality of flows (122) of data and each segment of data contains meta-data relating to that segment. The meta-data stored in the storage system (104) can be rebuilt in the event of a failure by scanning the meta-data in each segment. A first scan of the meta-data in each segment in the storage devices (106) identifies the last segment written from each flow (122) and these segments are excluded from the rebuilding process as they may contain incomplete or inconsistent information. A second scan of the meta-data in each segment in the storage devices (106) identifies any segments which do not contain any live data tracks and these segments are also excluded from the, rebuilding process. The meta-data in the storage system (104) can then be rebuilt using the meta-data in the segments, excluding those segments identified.
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Citations
27 Claims
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1. A method for rebuilding meta-data in a storage system having storage devices in which segments of data are located, wherein data is written in segments to the storage devices from a plurality of flows of data and each segment of data also contains meta-data relating to that segment;
- the method comprising;
scanning the meta-data in each segment to identify the last segment written from each flow;
rebuilding the meta-data in the storage system using the meta-data in the segments excluding the meta-data for the segments identified as being the last segments written from each flow. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
- the method comprising;
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14. A data storage system having storage devices in which segments of data are located, including a plurality of flows provided in the data storage system from which data is written in segments to the storage devices, each segment of data also containing meta-data relating to that segment;
wherein meta-data in the data storage system can be rebuilt using the meta-data in the segments excluding the meta-data for the segments identified as being the last segments written from each flow.
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27. A computer program product stored on a computer readable storage medium, comprising computer readable program code means for performing the steps of:
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scanning meta-data in each segment in storage devices to identify the last segment written from each of a plurality of flows of data;
rebuilding meta-data in the storage devices using the meta-data in the segments excluding the meta-data for the segments identified as being the last segments written from each flow.
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Specification