Xen and the Art of Open Source Virtualization
Virtual machine (VM) technology has been around for 40 years and has been experiencing a resurgence with commodity machines. VMs have been shown to improve system and network flexibility, availability, and security in a variety of novel ways. This paper introduces Xen, an efficient secure open source VM monitor, to the Linux community. Key features of Xen are:
- supports different OSes (e.g. Linux 2.4, 2.6, NetBSD, FreeBSD, etc.)
- provides secure protection between VMs
- allows flexible partitioning of resources between VMs (CPU, memory, network bandwidth, disk space, and bandwidth)
- very low overhead, even for demanding server applications
- support for seamless, low-latency migration of running VMs within a cluster
We discuss the interface that Xen/x86 exports to guest operating systems, and the kernel changes that were required to Linux to port it to Xen. We compare Xen/Linux to User Mode Linux as well as existing commercial VM products.