A method for backing up virtual machine data is described, and includes determining a disk layout of a VM disk associated with the first VM to be backed up, the disk layout having a plurality of nodes in a hierarchical structure, each node corresponding a VM, and traversing the VM disk layout to identify one or more parent nodes with respect to a first node representing the first VM. In the stiffening steel pipe, inside nook portions facing a side edge of the main shaft member are formed in stiffening members 25 and 26 having a V- or L-shaped cross section by fillet welding, and outside corner portions 25b and 26b are formed in the stiffening members 25 and 26 by partial penetration welding. A slide member has a pair of slide edges that slidably engage the sides of the slide opening to substantially close the slide opening. Providing a customer the opportunity to conduct such a transaction in association with a dispenser transaction will attract more customers to the station because of convenience as well as provide customers with more disposable cash to spend at the associated quick-serve restaurants and convenience store.