Distributed open writable snapshot copy facility using file migration policies
First Claim
1. A method comprising:
- a read-write snapshot copy facility creating a read-write snapshot copy of at least a portion of a production file system by creating stub files including pointers to data files in a read-only snapshot copy of at least the portion of the production file system; and
the read-write snapshot copy facility responding to a read request from an application program to read data from a read-write snapshot copy of at least a portion of one of the data files in the read-only snapshot copy of at least the portion of the production file system by accessing one of the stub files to obtain a pointer to said one of the data files, and using the pointer to said one of the data files to read data from said one of the data files and to return the data read from said one of the data files to the application program; and
the read-write snapshot copy facility responding to a write request from the application program to write data to a read-write snapshot copy of at least a portion of another of the data files in the read-only snapshot copy of at least the portion of the production file system by accessing another of the stub files to obtain a pointer to said another of the data files, and using the pointer to said another of the data files to read data from said another of the data files to produce a file that is written to by the application program and that replaces said another of the stub files.
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0 Petitions
Accused Products
Abstract
A read-write snapshot copy facility is constructed from a hierarchical storage management facility. The read-write snapshot copy file system initially comprises stub files pointing to the files in a read-only snapshot copy file system. When an application writes to a file in the read-write snapshot copy, the read-write snapshot copy facility migrates a copy of the file to replace the stub file, and then writes to the migrated file. Because the read-write snapshot copy facility references the files in the read-only snapshot file system in a network namespace using standard protocols such as NFS or CIFS, the read-write snapshot copy facility permits referencing of distributed read-only snapshot file systems in an open (heterogeneous) network environment, and the read-write snapshot copy is scalable by linking the read-write snapshot copy facility to multiple file servers containing read-only snapshot file systems.
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Citations
20 Claims
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1. A method comprising:
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a read-write snapshot copy facility creating a read-write snapshot copy of at least a portion of a production file system by creating stub files including pointers to data files in a read-only snapshot copy of at least the portion of the production file system; and the read-write snapshot copy facility responding to a read request from an application program to read data from a read-write snapshot copy of at least a portion of one of the data files in the read-only snapshot copy of at least the portion of the production file system by accessing one of the stub files to obtain a pointer to said one of the data files, and using the pointer to said one of the data files to read data from said one of the data files and to return the data read from said one of the data files to the application program; and the read-write snapshot copy facility responding to a write request from the application program to write data to a read-write snapshot copy of at least a portion of another of the data files in the read-only snapshot copy of at least the portion of the production file system by accessing another of the stub files to obtain a pointer to said another of the data files, and using the pointer to said another of the data files to read data from said another of the data files to produce a file that is written to by the application program and that replaces said another of the stub files. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus comprising a data processing device including storage and a read-write snapshot copy facility, the read-write snapshot copy facility being programmed for creating, in the storage of the data processing device, stub files including pointers to data files in a read-only snapshot copy of at least a portion of a production file system;
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the read-write snapshot copy facility being programmed for responding to a read request from an application program to read data from a read-write snapshot copy of at least a portion of one of the data files in the read-only snapshot copy of at least the portion of the production file system by accessing one of the stub files to obtain a pointer to said one of the data files, and using the pointer to said one of the data files to read data from said one of the data files and to return the data read from said one of the data files to the application program; and the read-write snapshot copy facility being programmed for responding to a write request from the application program to write data to a read-write snapshot copy of at least a portion of another of the data files in the read-only snapshot copy of at least the portion of the production file system by accessing another of the stub files to obtain a pointer to said another of the data files, and using the pointer to said another of the data files to read data from said another of the data files to produce a file that is written to by the application program and that replaces said another of the stub files. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification