Reference:
In Usenix Annual Technical Conference, 2011
Abstract:
Live migration enables a running virtual machine to move between two physical hosts with no perceptible interruption in service. This allows customers to avoid costly downtimes associated with hardware maintenance and upgrades, and facilitates automated load-balancing. Consequently, it has become a critical feature of enterprise class virtual infrastructure. In the past, live migration only moved the memory and device state of a VM, limiting migration to hosts with identical shared storage. Live storage migration overcomes this limitation by enabling the movement of virtual disks across storage elements, thus enabling greater VM mobility, zero downtime maintenance and upgrades of storage elements, and automatic storage load-balancing. We describe the evolution of live storage migration in VMware ESX through three separate architectures, and explore the performance, complexity and functionality trade-offs of each.
Full paper: [pdf] [Bibtex Entry]