Xen hypervisor gets speed boost

The tweaks in Xen 4.0 mean the update is fast enough even for network-intensive and high-performance computing applications, its developers have promised
Written by Matthew Broersma, Contributor

An update to the widely used open-source Xen hypervisor has been released, providing improvements to performance, scalability, memory usage and security, according to Xen.org.

The tweaks to Xen 4.0, unveiled on Tuesday, mean that the hypervisor is now suitable for network-intensive and high-performance computing applications, Citrix chief technology officer Simon Crosby said in a statement from Xen.org. Previously, it would not have been suitable for virtualisation of these applications for performance reasons, he said.

"The explosion of cloud computing in the industry and increasing demands from enterprise customers are the driving force behind the continued technology advancement of the Xen community," said Ian Pratt, chairman of Xen.org, in the statement.  

Citrix, along with companies such as IBM, Intel, HP, Novell, Red Hat and Oracle, is a member of the Xen Advisory Board (Xen AB), which oversees the development procedures for the Xen code. Xen draws on developer contributions from Xen AB members, as well as from several dozen other technology vendors, universities and virtualisation experts, according to the project. The hypervisor is also incorporated into commercial products from Citrix and others.

Performance improvements in Xen 4.0 include new algorithms, such as Transcendent Memory and Page Sharing, designed to improve the performance of memory operations, the project said.

In addition, the hypervisor includes a new virtual hard disk (VHD) implementation for delivering high-performance virtual-machine snapshots and cloning features.

On the hardware side, the hypervisor supports reliability, availability and serviceability (RAS) features found in new Intel Xeon and AMD Opteron processors. Besides this, it is tailored to newer developments in networking hardware, such as network interface cards with multi-queue and Single Root I/O Virtualisation (SR-IOV) features.

The Xen update also introduces support for PVOps in the Domain0 Linux kernel, an option that lets administrators access the most recent devices supported by the kernel.

Other improvements include better fault tolerance with support for live transactional synchronisation of virtual-machine states between physical servers as a basic component, which helps ensure service reliability, according to Xen.org. Administrators previously needed additional software to guarantee service levels.

The Xen hypervisor began as a research project at the University of Cambridge, and Xen.org is still based in Cambridge. Cambridge senior lecturer Pratt founded commercial hypervisor provider XenSource, which was acquired by Citrix in 2007.

Citrix's Xen-based technology includes XenApp, XenServer and Xen Desktop. The Nasa network that links the International Space Station to Earth currently uses Xen-based Citrix technology.

Among Xen's competitors is KVM, whose commercial developer Qumranet was acquired by Red Hat in 2008. Last year, Red Hat introduced the KVM hypervisor into its Red Hat Enterprise Linux distribution and is currently developing a new line of KVM-based virtualisation products called Red Hat Enterprise Virtualization (RHEV).

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