Online virtual machine disk migration
A method for migrating a virtual machine disk (VM disk) from first physical storage to second physical storage while the virtual machine (VM) is running, the method comprising: (a) creating a first child VM disk to which writes are redirected from a first parent VM disk, the first parent VM disk being on the first physical storage; (b) copying the first parent VM disk to the second physical storage as a second parent VM disk; (c) re-parenting the first VM child disk to the second parent VM disk; and (d) consolidating the first child VM disk and the second parent VM disk.
1. A method for migrating a virtual disk from first physical storage to second physical storage while an application execution environment depending on the virtual disk for execution is maintained in its physical location, the method comprising:
creating a first child virtual disk to which writes are redirected from a first parent virtual disk, the first parent virtual disk being on the first physical storage, wherein an application execution environment is dependent on the first parent virtual disk for execution;
copying the first parent virtual disk to the second physical storage as a second parent virtual disk while the application execution environment is running;
re-parenting the first virtual child disk to the second parent virtual disk; and
consolidating the first child virtual disk and the second parent virtual disk on the second physical storage;
wherein the first parent virtual disk is migrated from the first physical storage to the second physical storage without migrating the application execution environment.
2. The method of claim 1 further comprising stunning the application execution environment during the consolidating, such that writes to the first child virtual disk or the second parent virtual disk are not occurring during the consolidating.
3. The method of claim 1 further comprising deleting the first parent virtual disk from the first physical storage without migrating the application execution environment, such that the application execution environment has remained in its physical location while the first parent virtual disk on which the application execution environment is dependent for execution has been migrated.
4. The method of claim 1 wherein the physical storage on which the first child virtual disk is created is the first physical storage or the second physical storage or another physical storage.
5. The method of claim 1 further comprising, after the first child virtual disk is created:
designating the first parent virtual disk as read-only; and
redirecting writes intended for the first parent virtual disk to the first child virtual disk.
6. The method of claim 1 further comprising, prior to consolidating:
directing a read intended for the first parent virtual disk to the first child virtual disk if information associated with the read is unavailable in the first parent virtual disk.
7. The method of claim 1 wherein the first child virtual disk is represented as a file or as a raw device mapping.
8. The method of claim 1 wherein the first parent virtual disk is represented as a file or as a raw device mapping.
9. The method of claim 1 further comprising:
taking a snapshot of the first child virtual disk, whereby a second child virtual disk is created on physical storage;
redirecting writes intended for the first child virtual disk to the second child virtual disk; and
subsequent to consolidating the first child virtual disk and the second parent virtual disk, consolidating the second child virtual disk and the second parent virtual disk.
10. The method of claim 9 further comprising, prior to consolidating:
directing a read intended for the first parent virtual disk to the first child virtual disk if information associated with the read is unavailable in the first parent virtual disk; and
directing the read to the second child virtual disk if the information is unavailable in the first child virtual disk.
11. The method of claim 1 further comprising migrating the application execution environment from a first host platform to a second host platform.
12. A non-transitory computer-readable medium having computer-executable instructions for causing a virtualized computer system to perform a method migrating a virtual disk from first physical storage to second physical storage while an application execution environment depending on the virtual disk for execution is maintained in its physical location, the method comprising:
creating a first child virtual disk to which writes are redirected from a first parent virtual disk, the first parent virtual disk being on the first physical storage, wherein an application execution environment is dependent on the first parent virtual disk for execution;
copying the first parent virtual disk to the second physical storage as a second parent virtual disk while the application execution environment is running;
re-parenting the first virtual child disk to the second parent virtual disk; and
consolidating the first child virtual disk and the second parent virtual disk on the second physical storage;
wherein the first parent virtual disk is migrated from the first physical storage to the second physical storage without migrating the application execution environment.
13. The computer-readable medium of claim 12 wherein the method further comprises stunning the application execution environment during the consolidating, such that writes to the first child virtual disk or the second parent virtual disk are not occurring during the consolidating.
14. The computer-readable medium of claim 12 further comprises deleting the first parent virtual disk from the first physical storage without migrating the application execution environment such that the application execution environment has remained in its physical location while the first parent virtual disk on which the application execution environment is dependent for execution has been migrated.
15. The computer-readable medium of claim 12 wherein the method further comprises, after the first child virtual disk is created:
designating the first parent virtual disk as read-only; and
redirecting writes intended for the first parent virtual disk to the first child virtual disk.
16. The computer-readable medium of claim 12 wherein the method further comprises, prior to consolidating:
directing a read intended for the first parent virtual disk to the first child virtual disk if information associated with the read is unavailable in the first parent virtual disk.
17. The computer-readable medium of claim 12 wherein the first child virtual disk is represented as a file or as a raw device mapping.
18. The computer-readable medium of claim 12 wherein the first parent virtual disk is represented as a file or as a raw device mapping.
19. The computer-readable medium of claim 12 wherein the method further comprises:
taking a snapshot of the first child virtual disk, whereby a second child virtual disk is created on physical storage;
redirecting writes intended for the first child virtual disk to the second child virtual disk; and
subsequent to consolidating the first child virtual disk and the second parent virtual disk, consolidating the second child virtual disk and the second parent virtual disk.