VM migration system and VM migration method

A VM (virtual machine) migration system comprising a plurality of physical servers, each being configured to cause a plurality of VMs to run, and a controller connected to the plurality of physical servers and configured to manage running states of the VMs, wherein each of the plurality of physical servers includes a storage unit configured to store priority group setting information for a plurality of priority groups, the priority group setting information comprising, for each of the plurality of priority groups, (i) information on physical resources allocated to the respective priority group, (ii) information on VMs sharing the physical resources of the respective priority group, and (iii) a different number of VMs assignable to the respective priority group,

• wherein each of the plurality of the physical servers is configured to:
• collect an amount of resource usage for each VM running on a current priority group;
• transmit the collected amount of resource usage to the controller;
• and
• transmit the priority group setting information to the controller;
• wherein the controller is configured to:
• receive the amount of resource usage of each of the plurality of VMs and the priority group setting information from each of the plurality of physical servers;
• for each VM, calculate, for each respective priority group of the plurality of priority groups, a respective performance value based on the received amount of resource usage of the respective VM and the amount of physical resources allocated to the respective priority group;
• for each VM, determine a desired priority group by identifying a priority group having a calculated performance value that is (i) not below a first predetermined threshold indicating insufficient performance and (ii) not above a second predetermined threshold indicating excessive performance;
• determine whether a performance guarantee of each VM is possible, wherein the determination comprises:
• determining whether the current priority group meets the performance guarantee;
• in response to determining that the performance guarantee not being met by the current priority group, determining whether the desired priority group on the physical server the respective VM resides has room for the respective VM based on the priority group setting information;
• and
• outputting a performance guarantee failure alarm information in response to determining that the desired priority group has no room for the respective VM based on the priority group setting information;
• and
• in response to the outputted performance guarantee failure alarm information, perform the steps of:
• calculating a margin for each physical server indicating how much an available processing capacity exists for the respective physical server,
• selecting a physical server having a largest margin as another physical server to which the VM is to be migrated, and
• generating and transmitting migration instruction information to the physical server that the VM currently runs on, wherein the migration instruction information identifies the VM to be migrated, the another physical server having the largest margin to which the VM is to be migrated to;
• and
• wherein the physical server where migration instruction information are transmitted to is configured to:
• receive the migration instruction information from the controller and migrating the VM which is to be migrated to the physical server having the largest margin to which the VM is to be migrated to;
• and
• based on the migration instruction information, modify the priority group setting information on the physical server.