Systems and methods for a snapshot of data
View Patent ↗In one embodiment, a user or client device is connected to a distributed file system comprised of one or more physical nodes. The data on each of the physical nodes store metadata about files and directories within the file system. Some of the embodiments permit a user to take a snapshot of data stored on the file system. The snapshot may include a single file, a single directory, a plurality of files within a directory, a plurality of directories, a path on the file system that includes nested files and subdirectories, or more than one path on the file system that each includes nested files and directories. According to one embodiment, the system stores representations of the snapshots that govern a file or directory and its descendants within metadata associated with that file or directory. In one embodiment, before modifying a file or directory, the system updates the representations of the governing snapshots by traversing the metadata of ancestors of the file or directory.
1. A system for preserving access to previous versions of directories and files stored in a processor-accessible storage system, the system comprising:
at least one memory;
at least one computer processor;
a plurality of metadata structures logically arranged in a hierarchical structure and stored on the at least one memory, each metadata structure corresponding to a file or directory of a file system and comprising a governance list configured to store two or more snapshot identifiers, each snapshot identifier identifying a snapshot governing at least the corresponding file or directory, wherein the plurality of metadata structures comprises:
a target metadata structure that corresponds to a target file or directory of the file system; and
a parent directory metadata structure that corresponds to a parent directory of the file system that is a logical parent of the target file or directory; and
at least one executable software module executed by the at least one computer processor and configured to:
access a governance list of the parent directory metadata structure, wherein the governance list of the parent directory metadata structure is configured to store two or more snapshot identifiers, and wherein each snapshot identifier identifies a snapshot governing at least the parent directory;
identify a snapshot governing the parent directory that also governs the target file or directory and is not reflected in the governance list of the target metadata structure based on the accessed governance list of the parent directory metadata structure; and
add a snapshot identifier corresponding to the identified snapshot to a governance list of the target metadata structure.
2. The system of claim 1 , wherein the at least one executable software module is further configured to:
access a governance list of an ancestor directory metadata structure, wherein the ancestor directory metadata structure corresponds to an ancestor directory of the file system that is a logical ancestor of the parent directory of the target file or directory;
identify a snapshot governing the ancestor directory that also governs the target file or directory and is not reflected in the governance list of the target metadata structure based on the accessed governance list of the ancestor directory metadata structure; and
add a snapshot identifier corresponding to the identified snapshot to the governance list of the target metadata structure.
3. The system of claim 1 , wherein the at least one executable software module is further configured to:
receive a request to modify the target file or directory; and
modify the target file or directory.
4. The system of claim 3 , wherein the at least one executable software module is configured to the snapshot governing the parent directory that also governs the target file or directory after the target file or directory is modified.
5. The system of claim 4 , wherein the at least one executable software module is configured to identify the snapshot governing the parent directory that also governs the target file or directory as a result of the request to modify the target file or directory.
6. The system of claim 3 , wherein the at least one executable software module is configured to identify the snapshot governing the parent directory that also governs the target file or directory before the target file or directory is modified.
7. The system of claim 6 , wherein the at least one executable software module is configured to one or more snapshots identify the snapshot governing the parent directory that also governs the target file or directory as a result of the request to modify the target file or directory.
8. The system of claim 1 , wherein the at least one executable software module is further configured to:
receive a request to create a snapshot of a file or directory with one or more descendants;
create a snapshot of the file or directory and its one or more descendants; and
as a result of the request to create a snapshot, add a snapshot identifier to a governance list of a metadata structure corresponding to the file or directory but not to governance lists of metadata structures corresponding to the one or more descendants of the file or directory.
9. The system of claim 1 , wherein the at least one executable software module is configured to access governance lists of metadata structures corresponding to each ancestor file or directory of the target file or directory.
10. A method of preserving access to previous versions of directories and files stored in a processor-accessible storage system, the method comprising:
obtaining, by a computer processor, a plurality of metadata structures stored on at least one memory, each metadata structure corresponding to a file or directory of a file system and comprising a governance list configured to store two or more snapshot identifiers, each snapshot identifier identifying a snapshot governing at least the corresponding file or directory;
accessing, by the computer processor, a governance list of a parent directory metadata structure, wherein the parent directory metadata structure corresponds to a parent directory of the file system that is a logical parent of a target file or directory of the file system, wherein the governance list of the parent directory metadata structure is configured to store two or more snapshot identifiers, and wherein each snapshot identifier identifies a snapshot governing at least the parent directory at;
identifying, by the computer processor, a snapshot governing the parent directory that also governs the target file or directory and is not reflected in the governance list of the target metadata structure based on the accessed governance list of the parent directory metadata structure; and
adding, by the computer processor, a snapshot identifier corresponding to the identified snapshot to a governance list of a target metadata structure corresponding to the target file or directory.
11. The method of claim 10 , further comprising:
accessing a governance list of an ancestor directory metadata structure, wherein the ancestor directory metadata structure corresponds to a directory of the file system that is a logical ancestor of the parent directory of the target file or directory;
identifying a snapshot governing the ancestor directory that also governs the target file or directory and is not reflected in the governance list of the target metadata structure based on the accessed governance list of the ancestor directory metadata structure; and
adding a snapshot identifier corresponding to the identified snapshot to the governance list of the target metadata structure.
12. The method of claim 10 , further comprising:
receiving a request to modify the target file or directory; and
modifying the target file or directory.
13. The method of claim 12 , wherein the identifying is performed after the target file or directory is modified.
14. The method of claim 13 , wherein the identifying is performed as a result of the request to modify the target file or directory.
15. The method of claim 12 , wherein the identifying is performed before the target file or directory is modified.
16. The method of claim 15 , wherein the identifying is performed as a result of the request to modify the target file or directory.
17. The method of claim 10 , further comprising:
receiving a request to create a snapshot of a file or directory with one or more descendants;
creating a snapshot of the file or directory and its one or more descendants; and
as a result of the request to create a snapshot, adding a snapshot identifier to a governance list of a metadata structure corresponding to the file or directory but not to the governance lists of metadata structures corresponding to the one or more descendants of the file or directory.
18. The method of claim 10 , further comprising accessing the governance lists of metadata structures corresponding to each ancestor file or directory of the target file or directory.