Fast Wide Area Live Migration with a Low Overhead through Page Cache Teleportation

摘要

Live migration of virtual machines over a wide area network has many use cases such as cross-datacenter load balancing, low carbon virtual private clouds, and disaster recovery of IT systems. An efficient wide area live migration method is required because cross-datacenter connections have a narrow bandwidth. Page cache occupies a large portion of the memory of a Virtual Machine (VM) when it executes data-intensive workloads. We propose a new live migration technique, page cache teleportation, which reduces the total migration time of wide area live migration and has a low overhead. It detects the restorable page cache in the guest memory that has the same contents as the corresponding disk blocks. The restorable page cache is not transferred via the WAN but is restored from the disk image before the VM resumes. In this way, the IO performance degradation reduces after the migration. Evaluations show that page cache teleportation reduces the total migration time of wide area live migration and has a lower performance overhead than existing approaches.