The invention relates to apparatus for managing data swap in a migration of virtual memory data of a virtual machine. In one embodiment, an apparatus comprises a receiving unit configured to receive a migration instruction and the second site information; a copying unit configured to copy memory data to a sub-logical unit in the first storage device; and a notifying unit configured to send a notification to instruct the second host to read the memory data from a mirror logical unit of a sub-logical unit in the second storage device. The apparatus modifies a mirror direction between the first and second storage devices and modifies a path table related to the first and second storage devices. Data of the virtual machine can be migrated and swapped in a metro mirror manner, thereby the virtual machine data can be migrated across sites without affecting system operation.