Method and system for initializing a plurality of virtual machines sharing a physical storage unit managed by a storage system for storing a boot image used for initializing the plurality of virtual machines are provided. A data structure is maintained by a virtual machine monitor that manages the plurality of virtual machines. The data structure includes a file block number for accessing a boot image that can be used for initializing the plurality of virtual machines and a unique signature for the physical storage unit storing the boot image and a memory address of a cache memory where the boot image is stored after it is obtained from the storage system. The plurality of virtual machines is initialized using the boot image from the cached memory without having to obtain the boot image for each individual virtual machine except for a first virtual machine.