Avoiding full file replication using sparse files

Patent metadata

Field	Value
Publication number	US-10318489-B2
Application number	US-201514695482-A
Country	US
Kind code	B2
Filing date	Apr 24, 2015
Priority date	May 21, 2014
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

Examples disclosed herein provide systems, methods, and software for avoiding data replication using sparse files. In one example, a method of using a sparse file to manage modifications to read-only files includes identifying an open file request on a computing system for a read-only file, and generating the sparse file corresponding to the read-only file. The method further includes identifying a modification to the read-only file and, responsive to identifying the modification, initiate a write to the sparse file based on the modification and identifying the write in a region map.

First claim

What is claimed is:

1. A method of using a sparse file to manage modifications to read-only files, the method comprising:
identifying a request by a user of a plurality of users in a virtual machine of a plurality virtual machines to open a read-only file stored in a read-only volume attached to the virtual machine, the read-only file accessible by the plurality of users of the plurality of virtual machines via attachment of the read-only volume to the plurality of virtual machines;
in response to the request, generating the sparse file corresponding to the read-only file, wherein the sparse file is unique to the user of the virtual machine, and wherein the sparse file is stored in a writable volume attached to the virtual machine and associated with the user;
identifying a modification to the read-only file; and
responsive to identifying the modification, initiating a write to the sparse file based on the modification and identifying the write in a region map.

2. The method of claim 1 wherein generating the sparse file corresponding to the read-only file comprises, in a file system for the virtual machine, generating the sparse file corresponding to the read-only file.

3. The method of claim 2 wherein the sparse file comprises an equivalently sized sparse file to the read-only file.

4. The method of claim 1 further comprising: identifying a second modification to the read-only file; and
responsive to identifying the second modification, initiating a second write to the sparse file based on the second modification and identifying the second write in the region map.

5. The method of claim 1 further comprising:
identifying a second request by a second user of a second virtual machine to open the read-only file; and
in response to the second request, generating a second sparse file corresponding to the read-only file, wherein the second sparse file is unique to the second user of the second virtual machine, and wherein the second sparse file is stored in a second writable volume attached to the second virtual machine and associated with the second user.

6. The method of claim 1 wherein the read-only file comprises one of a text file, a database file, an image, or a HyperText Markup Language (HTML) file.

7. The method of claim 1 further comprising:
identifying a read request for the read-only file; and
retrieving data for the read request from one of the read-only file or the sparse file based on the region map.

8. The method of claim 1 wherein the read-only file is stored in a read-only volume available to the plurality of users, and wherein the sparse file is stored in a write volume available to the user.

9. An apparatus to manage modifications to read-only files, the apparatus comprising:
one or more non-transitory computer readable media;
processing instructions stored on the one or more non-transitory computer readable that, when executed by processing circuitry, direct the processing circuitry to:
identify a file request on by a user of a plurality of users in a virtual machine of a plurality of virtual machines to open a read-only file stored in a read-only volume attached to the virtual machine, the read-only file accessible by the plurality of users of the plurality of virtual machines via attachment of the read-only volume to the plurality of virtual machines;
in response to the request, generate a sparse file corresponding to the read-only file, wherein the sparse file is unique to the user of the virtual machine, and wherein the sparse file is stored in a writable volume attached to the virtual machine and associated with the user;
identify a modification to the read-only file; and
in response to identifying the modification, initiate a write to the sparse file based on the modification and identifying the write in a region map.

10. The apparatus of claim 9 wherein the processing instructions to generate the sparse file corresponding to the read-only file direct the processing circuitry to, in a file system for the virtual machine, generate the sparse file corresponding to the read-only file.

11. The apparatus of claim 10 wherein the sparse file comprises an equivalently sized sparse file to the read-only file.

12. The apparatus of claim 9 wherein the processing instructions further direct the processing circuitry to:
identify a second modification to the read-only file; and
in response to identifying the second modification, initiate a second write to the sparse file based on the second modification and identify the second write in the region map.

13. The apparatus of claim 9 wherein the processing instructions further direct the processing system to:
identify a second request by a second user of a second virtual machine to open the read-only file; and
in response to the second request, generate a second sparse file corresponding to the read-only file, wherein the second sparse file is unique to the second user of the second virtual machine, and wherein the second sparse file is stored in a second writable volume attached to the second virtual machine and associated with the second user.

14. The apparatus of claim 9 wherein the read-only file comprises one of a text file, a database file, an image, or a HyperText Markup Language (HTML) file.

15. The apparatus of claim 9 wherein the processing instructions further direct the processing circuitry to:
identify a read request for the read-only file; and
retrieve data for the read request from one of the read-only file or the sparse file based on the region map.

16. The apparatus of claim 9 wherein the read-only file is stored in a readonly volume available to the plurality of users, and wherein the sparse file is stored in a write volume available to the user.

17. The apparatus of claim 9 further comprising the processing circuitry.

18. A system to manage modifications to read-only files, the system comprising:
one or more read-only volumes that store read-only files accessible by a plurality of users on a plurality of virtual machines;
one or more writable volumes associated with a first user of the plurality of users; and an interpret module configured to:
in response to a request from the first user on a virtual machine of the plurality of virtual machines to open a read-only file stored on the one or more read-only volumes, generate a sparse file in the one or more writable volumes corresponding to the read-only file, wherein the sparse file is unique to the first user, wherein the one or more read-only volumes and the one or more writable volumes are attached to the virtual machine;
identify a modification to the read-only file; and
in response to identifying the modification, initiate a write to the sparse file based on the modification and identifying the write in a region map.

Assignees

• Vmware Inc

Inventors

• Choudhary Jairam
• Conover Matthew

Classifications

• G06F16/178 Primary

  Techniques for file synchronisation in file systems · CPC title

• G06F16/181

  providing write once read many [WORM] semantics · CPC title

• G06F2009/45579

  I/O management, e.g. providing access to device drivers or storage · CPC title

• G06F16/1744 Primary

  using compression, e.g. sparse files · CPC title