The present invention relates generally to a storage system for managing storage apparatuses and, more particularly, to a method and a system for deploying a virtual hard disk file to a virtual volume known as thin provisioning.
The use of virtual hard disk (VHD) has been widespread in accordance with the growth of server virtualization technology. In addition, the virtual appliance which packs virtual server specification and the VHD into one package has also grown in usage. The VHD can be recognized as a logical volume by the virtual machine even though the VHD is recognized as just a file by the physical server because the hypervisor converts the VHD file dynamically and presents it as a volume to the virtual machine. The VHD has a thin provisioning functionality that grows its actual capacity on demand. On the other hand, the thin provisioning functionality has also been implemented in a storage apparatus such as the Hitachi Dynamic Provisioning of Hitachi USP/V. In that case, the virtual volume is presented as a logical unit that can be accessed through a fiber channel mainly from the physical server.
Migration between the virtual server and physical server is increasingly popular based on the requirement for performance and availability of the application system. However, the physical server cannot access the VHD as a logical drive. Conversion of the VHD to a logical device is necessary for the use of the VHD by the physical server. In that case, if the VHD is converted to a fixed-size logical device, it creates a problem that the capacity efficiency decreases. Furthermore, in the case where the VHD is converted to a virtual device (logical device with thin provisioning), if there is a gap between the page size of the virtual device and the block size of the VHD, the capacity efficiency is not fully realized.