System and method for restoring a virtual disk from a snapshot

An apparatus to restore a virtual disk (vdisk) in an active file system to an earlier time, comprising:

• means for maintaining pointers pointing to data represented by the virtual disk;
• means for saving the pointers to persistent storage at the earlier time;
• means for comparing a pointer at a later time with the pointers saved at the earlier time;
• if the pointer from the later time matches the pointer saved at the earlier time, means for keeping the pointer from the later time in the active file system;
• and
• if the pointer from the later time does not match the pointer saved at the earlier time, means for copying a set of pointers associated with the pointer saved at the earlier time to the active file system.

An apparatus to restore a virtual disk (vdisk) in an active file system to an earlier time, comprising:

• an operating system to maintain pointers pointing to data represented by the virtual disk;
• one or more storage disks to save the pointers to persistent storage at the earlier time;
• a processor to compare a pointer at a later time with the pointers saved at the earlier time;
• if the pointer from the later time matches the pointer saved at the earlier time, the processor to keep the pointer from the later time in the active file system;
• and
• if the pointer from the later time does not match the pointer saved at the earlier time, the processor to copy a set of pointers associated with the pointer saved at the earlier time to the active file system.

A computer readable media, comprising:

• said computer readable media containing instructions for execution on a processor for the practice of a method for restoring a virtual disk (vdisk) in an active file system to an earlier time, the method having the steps of,
• maintaining pointers pointing to data represented by the virtual disk;
• saving the pointers to persistent storage at the earlier time;
• comparing a pointer at a later time with the pointers saved at the earlier time;
• if the pointer from the later time matches the pointer saved at the earlier time, keeping the pointer from the later time in the active file system;
• and
• if the pointer from the later time does not match the pointer saved at the earlier time, copying a set of pointers associated with the pointer saved at the earlier time to the active file system.

A method for restoring a virtual disk (vdisk) in an active file system to an earlier time, the method comprising the steps of:

• maintaining pointers pointing to data represented by the virtual disk, the pointers arranged in an inode structure;
• saving the inode structure to persistent storage at the earlier time;
• creating a twin inode at a later time, the twin inode being a duplicate of the inode structure of the vdisk at the later time;
• comparing a pointer from the twin inode with a pointer saved at the earlier time;
• if the pointer from the twin inode matches the pointer saved at the earlier time, moving the pointer from the twin inode to the active file system;
• and
• if the pointer from the twin inode does not match the pointer saved at the earlier time, copying a set of pointers associated with the pointer saved at the earlier time to the active file system.

A computer readable media, comprising:

• said computer readable media containing instructions for execution on a processor for the practice of a method for restoring a virtual disk (vdisk) in an active file system to an earlier time, the method having the steps of,
• maintaining pointers pointing to data represented by the virtual disk, the pointers arranged in an inode structure;
• saving the inode structure to persistent storage at the earlier time;
• creating a twin inode at a later time, the twin inode being a duplicate of the inode structure of the vdisk at the later time;
• comparing a pointer from the twin inode with a pointer saved at the earlier time;
• if the pointer from the twin inode matches the pointer saved at the earlier time, moving the pointer from the twin inode to the active file system;
• and
• if the pointer from the twin inode does not match the pointer saved at the earlier time, copying a set of pointers and associated with the pointer saved at the earlier time to the active file system.

An apparatus to restore a virtual disk (vdisk) in an active file system to an earlier time, comprising:

• means for maintaining pointers pointing to data represented by the virtual disk, the pointers arranged in an inode structure;
• means for saving the inode structure to persistent storage at the earlier time;
• means for creating a twin inode at a later time, the twin inode being a duplicate of the inode structure of the vdisk at the later time;
• means for comparing a pointer from the twin inode with a pointer saved at the earlier time;
• if the pointer from the twin inode matches the pointer saved at the earlier time, means for moving the pointer from the twin inode to the active file system;
• and
• if the pointer from the twin inode does not match the pointer saved at the earlier time, means for copying a set of pointers associated with the pointer saved at the earlier time to the active file system.

An apparatus to restore a virtual disk (vdisk) in an active file system to an earlier time, comprising:

• an operating system to maintain pointers pointing to data represented by the virtual disk, the pointers arranged in an inode structure;
• one or more storage disks to save the inode structure to persistent storage at the earlier time;
• as processor to create a twin inode at a later time, the twin inode being a duplicate of the inode structure of the vdisk at the later time;
• an operating system to compare a pointer from the twin inode with a pointer saved at the earlier time;
• if the pointer from the twin inode matches the pointer saved at the earlier time, the operating system to move the pointer from the twin inode to the active file system;
• and
• if the pointer from the twin inode does not match the pointer saved at the earlier time, the operating system to copy a set of pointers associated with the pointer saved at the earlier time to the active file system.