1. A data migration method comprising: storing, by a first control processor that operates in a first physical machine and that controls a first cache memory in the first physical machine storing first cache data cached from first storage data stored in a storage, first management information in a first storage including information indicating a storage location of the first cache data on the first cache memory, state information indicating whether the first storage data has been updated in accordance with an update of the first cache data for each block of a predetermined data size in the first cache memory, identification information of the first cache data corresponding to each block in the first cache memory and information indicating whether the first cache data is stored for each block in the first cache memory, when a program that accesses the first cache data migrates to a different node, setting, by the first control processor, information indicating that cache data is not stored in all blocks in the first management information and transmitting, by the first control processor, the first management information stored in the first storage to a second control processor that operates in a second physical machine and that controls a second cache memory in the second physical machine capable of being accessed by the program after migration to the different node, when new cache data to be stored in a block corresponding to information indicating that cache data is not stored among the first management information transmitted from the first control processor is acquired from the first storage data and stored in the second cache memory, setting, by the second control processor, information indicating that the acquired new cache data is stored in the first management information transmitted from the first control processor, acquiring, by the second control processor, the first cache data stored in a block indicating that cache data is not stored in the first cache memory based on information indicating whether or not cache data corresponding to each block is stored among the first management information transmitted from the first control processor, setting, by the second control processor, information indicating that cache data is stored in a block corresponding to the acquired first cache data to the first management information transmitted from the first control processor and storing, by the second control processor, the acquired first cache data in the second cache memory, and specifying, by the second control processor, cache data corresponding to the block corresponding to the first storage data that is not updated among the stored first cache data based on the first management information transmitted from the first control processor, and first updating, by the second control processor, the first storage data based on the specified cache data.