Incremental disk backup
First Claim
1. A distributed data processing system including a plurality of processing nodes and a plurality of data storage disks which are shared between the nodes and each have a plurality of data blocks, each node storing a respective incremental backup bit-file containing one bit for each block on the shared disks, the respective bit being set when a said node writes data to a said block;
- means for reading the bit-files of all nodes, forming the logical OR thereof and producing a corresponding new incremental backup bit-file; and
means for performing incremental backup in accordance with the new incremental backup bit-file.
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Accused Products
Abstract
Each node of a distributed (multi-node) data processing system, which includes a plurality of shared data storage disks, has a respective incremental backup bit-file containing one bit for each datablock of the shared disks. The bits are initially set to logical 0. When a node writes data to a datablock the respective bit is reset to logical 1. Upon an incremental backup requirement, one node reads all of the bit-files, forms the logical OR thereof and forms a respective new bit-file. The blocks whose bits equal 1 in this new bit-file are then backed up. The bit-files are stored in the node main memories for quick access and will be lost upon node failure. However if a redo log is maintained, bit-files can be reconstructed.
38 Citations
18 Claims
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1. A distributed data processing system including a plurality of processing nodes and a plurality of data storage disks which are shared between the nodes and each have a plurality of data blocks, each node storing a respective incremental backup bit-file containing one bit for each block on the shared disks, the respective bit being set when a said node writes data to a said block;
- means for reading the bit-files of all nodes, forming the logical OR thereof and producing a corresponding new incremental backup bit-file; and
means for performing incremental backup in accordance with the new incremental backup bit-file. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- means for reading the bit-files of all nodes, forming the logical OR thereof and producing a corresponding new incremental backup bit-file; and
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9. A method for achieving incremental backup in a distributed data processing system including a plurality of processing nodes and a plurality of data storage disks'"'"' shared between the nodes and each having a plurality of data blocks, including the steps of storing a respective incremental backup bit-file at each node, the backup bit-files each containing one bit for each block on the shared disks;
- setting the respective bit when a said node writes data to a said block; and
when incremental backup is required, reading the bit files of all nodes, forming the logical OR thereof and producing a corresponding new incremental backup bit-file, and performing incremental backup in accordance with the new incremental backup bit-file. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
- setting the respective bit when a said node writes data to a said block; and
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17. A distributed data processing system including:
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a plurality of processing nodes; a plurality of data storage disks, shared between the nodes, each having a plurality of data blocks; a network interconnecting the nodes; each node having a memory in which is stored a respective incremental backup bit-file containing one bit for each data block on the shared disks, which bits are initially set to a first of two possible states, and each node having means for setting the respective bit in its backup bit-file to the other of the two possible states when that node writes data to one of said data block; at least one of said nodes including means for reading the backup bit-files of all of the nodes and forming the logical OR thereof, and producing a corresponding new incremental backup bit-file; and the system including means for performing incremental backup in accordance with the new incremental backup bit-file by backing up those blocks whose bit-file bits are set to the other state.
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18. A method for achieving incremental backup in a distributed data processing system including a plurality of processing nodes each having a respective memory, a plurality of data storage disks each having a plurality of datablocks, the disks being shared between the nodes, the method including the steps of:
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storing in the memory of each node a respective incremental backup bit-file containing one bit for each datablock on the shared disks, which bits are initially set to a first of two possible states, and setting the respective bit in a said backup bit-file to the other of the two possible states when the respective node writes data to one of said datablocks; and wherein when incremental backup is required, causing one of said nodes to read the backup bit-files of all of the nodes, to form the logical OR thereof and to produce a corresponding new incremental backup bit-file, and performing incremental backup in accordance with the new incremental backup bit-file by backing up those blocks whose bits are set to the other state.
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Specification