Patent ID: 8694746
Filing Date: 2014-04-08
Classification: G06F

Abstract:
1. A method for synchronizing copies of a virtual disk, the method comprising the steps of: maintaining, by a virtualization layer supporting execution of virtual machines, a first record of file system blocks of a first copy of the virtual disk that are modified during an access session by a virtual machine using the first copy of the virtual disk, wherein the file system blocks correspond to a file system of the virtual disk that is used by a guest operating system of the virtual machine to access the first copy of the virtual disk; and during an attempt to synchronize the first copy with a second copy of the virtual disk, (i) obtaining, from the guest operating system, a second record of file system blocks that are currently used by the file system, and (ii) comparing the first record and the second record to determine file system blocks that are modified during the access session and currently used by the file system based on the file system blocks in the first copy of the virtual disk that are present in both the first record and the second record, (iii) copying, into the second copy of the virtual disk, the determined file system blocks in the first copy of the virtual disk such that file system blocks that are modified during the access session and currently used by the file system are copied and any file system blocks modified during the access session that are no longer being used by the file system are not copied.