Patent ID: 8032883

Claim:
A computer machine comprising: a local disk; a memory; a virtual machine monitor configured to run in the computer machine; virtual machines configured to run on the virtual machine monitor wherein the virtual machines comprises a client virtual machine and a file server virtual machine in which an internal file server accessible from the client virtual machine is executed; a virtual machine manager configured to manage a part of the local disk and a part of the memory and to control booting of the virtual machines; a monitoring module configured to monitor whether a communication with an external server in which an external file server is executed via a network is possible; an access control module configured to access a file in the external file server or the internal file server from the client virtual machine, wherein the monitoring module determines that the communication with the external server from the client virtual machine is impossible the access control module further configured to write-access a file in the part of the local disk or in the part of the memory, which are managed by the virtual machine manager, when the monitoring module determines that the communication with the external server is impossible during a first time period after determining that the communication with the external server via the network is possible, wherein the communication with the external server is determined to be impossible when a response is not issued from the external server; a file deletion module configured to delete the write-accessed file in the part of the local disk or in the part of the memory when the monitoring module determines that the communication with the external server is impossible during a second time period, which is longer than the first time period, after determining that the communication with the external server via the network is possible and; wherein the monitoring module further configured to instruct the virtual machine manager to perform a forced termination or a suspend of the client virtual machine when the monitoring module detects that the communication is impossible, and the virtual machine manager further configured to perform the forced termination or the suspend of the client virtual machine according to an instruction from the monitoring module.