Online storage volume shrink

• US 7,409,523 B2
• Filed: 12/16/2005
• Issued: 08/05/2008
• Est. Priority Date: 12/16/2005
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Buban, Garret J., Pudipeddi, Ravisankar V., Seng, Kevin Y.
• Primary Examiner(s): Kim; Matt
• Assistant Examiner(s): PATEL, HETUL B
• Application Number:
  US11/303,419
• Publication Number:
  US 20070143563A1
• Time in Patent Office: 963 Days
• Field of Search: 711/162, 711/173
• US Class Current: 711/173
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0676 Magnetic disk device

Abstract

Described is a technology by which a new volume or partition may be created on a disk, e.g., by running a shrink program and then reclaiming freed space. Shrink occurs online, while the user or system processes may be otherwise using the disk for reads and writes. Further, the technology operates while protecting snapshot versions of the volume. To shrink, upon receiving a request to shrink a volume to within a boundary, new allocations are restricted such that any allocation is to a volume area within the boundary. Data is moved from outside the boundary to within the boundary, and the shrink is committed when no volume data remains outside the boundary. A reduced-size volume or partition that does not include the specified region is committed when the data has been moved out of the specified region. A new volume or partition may be freed that corresponds to the region.

Claims

1. At least one computer storage medium for implementing a method for online shrinking of a volume, the at least one computer storage medium having computer-executable instructions stored thereon, which, when executed at a processor, perform steps of the method, including:

accessing volume information for a volume, the volume information indicating that the volume is between a first boundary and a second boundary on a computer storage medium, the first boundary and second boundary defining the size of the volume;

receiving a request to shrink the volume, the request including a shrink boundary that is to be placed between the first boundary and the second boundary on the computer storage medium;

restricting allocations such that any new allocation is in an first area of the volume, the first area being the area between the first boundary and shrink boundary;

initiating moving volume data from a second area, the second area being the area between the shrink boundary and the second boundary, to the first area to create a shrink region between the shrink boundary and the second boundary, the shrink region representing freed up space that can be used for a new volume on the computer storage medium;

receiving a request for a new allocation subsequent to initiating and during the movement of volume data from the second area to the first area;

allowing the new allocation request to a location only in the first area during and in parallel with the movement of volume data from the second area to the first area; and

committing the shrink when no volume data remains within the second area.

2. The at least one computer storage medium of claim 1 having further computer-executable instructions comprising, estimating whether sufficient space exists within the boundary to move the data.

3. The at least one computer storage medium of claim 2 wherein estimating whether sufficient space exists comprises locating any known unmovable files.

4. The at least one computer storage medium of claim 2 wherein estimating whether sufficient space exists comprises requesting that snapshot data not presently in a differential area be associated with the differential area.

5. The at least one computer storage medium of claim 4 wherein estimating whether sufficient space exists comprises factoring in a buffer to provide for differential area growth.

6. The at least one computer storage medium of claim 4 wherein estimating whether sufficient space exists comprises obtaining information from a volume snapshot mechanism corresponding to differential area size data.

7. The at least one computer storage medium of claim 1 wherein moving the volume data is performed asynchronously.

8. The at least one computer storage medium of claim 1 wherein the volume is shrunk to be at the front of a disk, by restricting the new allocations to be before the shrink boundary and moving the volume data from beyond the shrink boundary to before the shrink boundary.

9. The at least one computer storage medium of claim 1 having further computer-executable instructions comprising, creating at least one new volume and/or partition within the shrink region.

10. The at least one computer storage medium of claim 9 wherein one volume and/or partition is created at the end of a disk.

11. In a computing environment having at least one computing device, a system comprising:

a processor;

system memory; and

at least one computer storage medium having stored thereon a shrink engine and a file system component,

wherein the shrink engine is configured to;

access volume information for a volume, the volume information indicating that the volume is between a first boundary and a second boundary on a computer storage medium, the first boundary and second boundary defining the size of the volume;

receive requests to shrink volumes, the requests including a shrink boundary that is to be placed between the first boundary and the second boundary on the computer storage medium, placement of the shrink boundary resulting in a first area being the area between the first boundary and the shrink boundary and a second area being the area between the shrink boundary and the second boundary;

initiating moving volume data from a second area to the first area to create a shrink region between the shrink boundary and the second boundary, the shrink region representing freed up space that can be used for a new volume on the computer storage medium; and

wherein the file system component communicates with the shrink engine and the file system component configured to;

allow allocations only in the first area while allowing read operations from any location of the volume and/or partition;

move volume data from the first area to the second area;

receive requests for new allocations subsequent to initiating and during the movement of volume data from the second region to the first region; and

allow new allocation requests to a location in the first area during and in parallel with the movement of volume data from the second area to the first area; and

wherein the shrink engine is further configured to commit shrinks when no volume data remains within the second area.

12. The system of claim 11 further comprising, a volume snapshot mechanism that communicates with the shrink engine and/or file system to preserve snapshot-related data.

13. The system of claim 11 wherein the shrink engine is further configured to cancel a shrink operation.

14. The system of claim 11 wherein the shrink engine if further configured to provide information corresponding to progress of moving the volume data from the second area to the first area.