Efficient routing and bandwidth assignment for inter-data-center live virtual-machine migrations

Using virtualization, service providerscan create an abstraction of the physical servers hosted in their data centers, and run their services directly on these abstract entities, called virtual machines (VMs). As a direct result of service virtualization, services hosted on VMs can be migrated from one data center to another. VMmigration can be performed without or with a minimal service interruption, and in this case we talk about live VM migration. The main issue of live VM migration is that memory pages are modified during the process. Due to this fact, the same memory pages might be transferred several times, thus increasing both the migration duration and the amount of network resources occupied by the VM migration process. Considering the increasing amount of VM migrations carried on in inter-data-center networks, efficient strategies for live-VM-migration bandwidth provisioning are needed. In this paper, we propose and compare various novel routing and bandwidth assignment algorithms for the live migration of VMs in a distributed DC infrastructure, under dynamic traffic conditions. We find that assigning a bandwidth to theVMmigration request in proportion to the path length with the objective of minimizing the amount of resources occupied by the migration request could improve the network performance. In addition,wepresent a comparative analysis of the serial and the parallel migration of multiple VMs.We quantify the impact of the migration strategy (serial versus parallel) on blocking probability, migration duration, downtime, and resource occupation.