Virtually infinite reliable storage across multiple storage devices and storage services

• US 20060230076A1
• Filed: 04/08/2005
• Published: 10/12/2006
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Bolosky, William J., Douceur, John R., Teodosiu, Dan, Kuppusamy, Ashok, Gounares, Alexander G., Endres, Raymond E.
• Granted Patent: US 8,010,498 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 9/38 Concurrent instruction execution, e.g. pipeline or look ahead

Abstract

A logical file system is described that distributes copies of files across various different physical storage resources yet provides a consistent view to the user of his or her data, regardless of which machine the user is accessing the files from, and even when the user'"'"'s computer is offline. The distributed file system uses smart data redundancy to enable a virtually infinite amount of storage as long as additional storage resources are made available to the distributed file system. The result is a reliable storage system that does not necessarily tie the user'"'"'s data to the user'"'"'s particular computer. Instead, the user'"'"'s data is associated with the user—for life—or for however long the user would like the data to be maintained, regardless of whether the user'"'"'s computer or data storage components are replaced or destroyed.

Claims

1. A computer-readable medium storing computer-executable instructions for performing steps comprising:

replicating file directory information such that both a first volume and a second volume store the same file directory information, wherein the file directory information identifies at least a plurality of files;

replicating file metadata for the plurality of files such that both the first volume and the second volume store the same file metadata for the plurality of files; and

replicating file data for at least some of the plurality of files such that the first volume stores a first subset of the plurality of files and the second volume stores a second subset of the plurality of files.

2. The computer-readable medium of claim 1, wherein the first volume is a local volume, and wherein the second volume is cloud storage provided by a service provider.

3. The computer-readable medium of claim 1, wherein the first volume is a local volume, and wherein the second volume is a non-local volume.

4. The computer-readable medium of claim 1, wherein the computer-executable instructions are further for performing steps comprising:

detecting an addition of a third volume;

responsive to detecting the addition of the third volume, replicating file directory information from at least one of the first or second volumes onto the third volume such that the third volume stores the same file directory information as the first and second volumes;

responsive to detecting the addition of the third volume, replicating the file metadata from at least one of the first or second volumes onto the third volume such that the third volume stores the same file metadata as the first and second volumes; and

replicating a third subset of the plurality of files onto the third volume different from the first and second subsets.

5. The computer-readable medium of claim 4, wherein the computer-executable instructions are further for performing steps comprising:

detecting unavailability of the third volume; and

responsive to detecting the unavailability of the third volume, replicating a third subset of the plurality of files between the first and second volumes.

6. The computer-readable medium of claim 5, wherein the computer-executable instructions are further for determining the third subset based on a comparison of, for each of the plurality of files that had content stored on the third volume prior to detecting unavailability of the third volume, a predetermined number of replications and an existing number of replications of the file.

7. The computer-readable medium of claim 6, wherein the computer-executable instructions are further for providing an interface that presents the plurality of files to an application or to a user as all being stored on a single volume.

8. The computer-readable medium of claim 1, wherein the computer-executable instructions are further for performing steps of:

receiving a user request directed to the first volume to read a first file of the plurality of files;

responsive to the user request, determining which volume stores content of the first file;

if the content of the first file is stored on the second volume, then replicating the content of the first file from the second volume to the first volume; and

reading the content of the first file from the first volume.

9. The computer-readable medium of claim 1, wherein the computer-executable instructions are further for performing steps of:

receiving a user request directed to the first volume to read a first file of the plurality of files;

responsive to the user request, determining a volume that stores content of the first file; and

reading the content of the first file from either the first volume or the second volume depending upon which volume stores the content of the first file.

10. The computer-readable medium of claim 1, wherein the computer-executable instructions are further for performing steps of:

creating a new file;

storing the new file on the first volume;

detecting that the new file has been closed;

responsive to detecting that the new file has been closed, replicating the new file to the second volume.

11. The computer-readable medium of claim 1, wherein the computer-executable instructions are further for performing steps of:

selecting an existing file to modify;

replicating the file from the second volume to the first volume;

replacing the file with a modified version of the file on the first volume;

detecting that the modified version of the file has been closed; and

responsive to detecting that the modified version of the file has been closed, replicating the modified version of the file from the first volume to the second volume.

12. A computer-readable medium storing computer-executable instructions for performing steps comprising:

defining a storage policy;

replicating a same file directory to each of a plurality of volumes, the directory referencing a plurality of files;

replicating a same file metadata for the plurality of files to each of the plurality of volumes;

for each of the plurality of files, replicating the file to a subset of the plurality of volumes to generate a number of file replications that depends upon the storage policy; and

for each of the plurality of files, storing each file replication in at least one of the plurality of volumes, wherein at least two volumes of the plurality of volumes contain different subsets of the file replications.

13. The computer-readable medium of claim 12, wherein the storage policy defines a different number of replications for each of different types of files.

14. The computer-readable medium of claim 12, wherein the computer-executable instructions are further for updating the directory on each of the plurality of volumes in response to the directory stored on one of the plurality of volumes being modified.

15. The computer-readable medium of claim 12, wherein the computer-executable instructions are further for performing steps of:

detecting an addition of a new volume to the plurality of volumes;

responsive to detecting the addition of the new volume, replicating the directory to the new volume; and

responsive to detecting the addition of the new volume, replicating the file metadata for the plurality of files to the new volume.

16. The computer-readable medium of claim 12, wherein the computer-executable instructions are further for performing steps comprising:

detecting unavailability of a first volume in the plurality of volumes; and

responsive to detecting the unavailability of the first volume;

determining a subset of the plurality of files that were stored on the first volume, and

for each file of the subset of the plurality of files, generating a file replication from a copy of the file stored on one of the plurality of volumes and storing the file replication on another of the plurality of volumes.

17. The computer-readable medium of claim 16, wherein the first volume is a primary volume, and wherein the computer-executable instructions are further for selecting a new primary volume from the plurality of volumes responsive to detecting unavailability of the first volume.

18. The computer-readable medium of claim 12, wherein the computer-executable instructions are further for providing an interface that presents the plurality of files to an application or to a user as all being stored on a single volume of the plurality of volumes.

19. The computer-readable medium of claim 12, wherein the computer-executable instructions are further for performing steps of:

receiving a user request directed to a first volume of the plurality of volumes to read a first file of the plurality of files;

responsive to the user request, determining which of the plurality of volumes stores content of the first file;

if the content of the first file is stored on a second volume of the plurality of volumes, then replicating the content of the first file from the second volume to the first volume; and

reading the content of the first file from the first volume.

20. The computer-readable medium of claim 12, wherein the computer-executable instructions are further for performing steps of:

receiving a user request directed to a first volume of the plurality of volumes to read a first file of the plurality of files;

responsive to the user request, determining whether the first volume stores content of the first file;

if the first volume does not store the content of the first file, then determining a second volume of the plurality of volumes that stores the content of the first file; and

reading the content of the first file from either the first volume or the second volume depending upon which volume stores the content of the first file.

21. The computer-readable medium of claim 12, wherein the computer-executable instructions are further for performing steps of:

creating a new file;

storing the new file on a first volume of the plurality of volumes;

detecting that the new file has been closed;

responsive to detecting that the new file has been closed, replicating the new file to a number of other volumes of the plurality of volumes that depends upon the storage policy.

22. A computer-assisted method, comprising:

defining a storage policy;

replicating a same file directory to each of a plurality of volumes, the directory referencing a plurality of files;

replicating a same file metadata for the plurality of files to each of the plurality of volumes;

for each of the plurality of files, replicating the file to generate a number of file replications that depends upon the storage policy; and

for each of the plurality of files, storing each file replication in at least one of the plurality of volumes, wherein at least two volumes of the plurality of volumes contain different subsets of the file replications.