Live WAN VM Migratinppt生活migrationppt万VM.pptVIP

Robert Bradford, Evangelos Kotsovinos, Anja Feldmann, Harald Schi?berg Presented by Kit Cischke Differences in Contributions The first paper discussed transferring run-time memory of a VM in a LAN. Cool. This paper expands on that to transfer the VM’s image, its persistent state and on-going network connections over a WAN as well. By combining pre-copying, write-throttling and a block-driver, we can achieve this. Introduction In this project, the authors want to extend live VM migration to include: Persistent state (file systems used by the VM) Open network connections Why? Many apps running on a VM need that storage, and NAS systems may not be available in the new location. Moving across a WAN will almost certainly involve an IP change, and we don’t want to (overly) disrupt TCP connections. Contribution A system enables live migration of VMs that use local storage and open network connections without severely disrupting their live services. Highlights Some highlights of this work: Built upon the Xen Live Migration facility as part of XenoServer. Enables: Live migration Consistency Minimal Service Disruption Transparency Utilizes: Pre-copying, write-throttling and IP tunneling. System Design - Environment Both the source and destination run Xen, with the VM running XenLinux. Uses blocktap to export block devices into the migrated VM. Block devices are file-backed meaning the contents of the block device are stored in an ordinary file on the file system of the VM. System Design - Architecture The initialization stage starts things off by prepping the migration. The bulk transfer stage pre-copies the disk image of the VM to the destination while the VM continues to run. Xen transfer is then initiated, which performs incremental migration, again without stopping the VM. While the transfers are occurring, all disk writes are intercepted as deltas that will be forwarded to the destination. Deltas include the data written, the location written and the size of the dat