Virtual Disk File Format Conversion Method and Apparatus

A virtual disk file format conversion method and an apparatus that relate to the field of virtualization technologies and to resolve a service interruption caused by offline conversion of a virtual machine disk image file format when a virtual machine is migrated between different types of VMMs. The method and apparatus include establishing a mapping table between a virtual address of a virtual machine (VM) disk image file and a physical address of a disk image file that is compatible with a virtual machine monitor (VMM), converting, according to the mapping table, the virtual address used when a user performs reading/writing on the VM disk image file, into the physical address mapped to the virtual address, and performing data reading/writing on the VM disk image file based on the physical address.