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Emulating a part of computer hardware is a trend in recent virtual machine research. For example, Xen and Denali call such emulation para-virtualization. Xen is a mainframe-type virtual machine monitor for IA-32 [Xen03]. Xen replaces hardware interrupts with its own event system. Xen allows guest operating systems read access to page tables but it mediates write access. Xen hosts Linux and Windows XP. Denali is a virtual machine monitor for distributed and networked systems [Denali03]. Denali has its own memory management mechanism and interrupts. Denali runs thousands of the Ilwaco guest OS. Compared with those systems, our virtual machine differs in that we use a language processor (the assembler preprocessor). Both Xen and Denali require porting effort when they need to execute existing native operating systems.
Virtualizing Linux with Xen: Xen is a para-virtualization technology available for the Linux kernel that can offer users a chance to enclose and test new upgrades as if running them in the existing environment, but without the worries of disturbing the original system. In this article, we look at virtualization on Linux and determine the benefits that come from using Xen in that space. (Articles)
Analyst Reaction to EMC's VMware Bid Mixed
December 30, 2003
By Clint BoultonWhen EMC (Quote, Chart) announced its intent to purchase VMware two weeks ago, many technology analysts greeted the news with praise while their Wall Street counterparts balked, citing a lack of synergy between server virtualization and EMC's core competency, storage.
Count Susquehanna Financial Group among the doubters of EMC's $635 million bid, which it says is expensive considering VMware's 2003 sales.
While encouraged by EMC's earlier purchases of Legato Systems and Documentum to bolster the company's information lifecycle management (ILM) strategy, Susquehanna views EMC's interest in VMware as largely impractical.
"VMware provides little synergy with storage, whereas Legato and Documentum are building on EMC's Information Lifecycle Management strategy," a Susquehanna report said. "VMware, which makes server provisioning software for Windows and Linux environments, is in a different space altogether."
Susquehanna analysts Kaushik Roy and Phillip Rowe also voiced concern that VMware's revenues are from a low price-point software product with limited growth potential.
VMware offers a number of products, but most revenue comes from software licenses of VMotion, ESX server, and GSX server. VMotion helps customers consolidate servers by migrating applications from smaller servers to new, higher-end servers with no downtime for the applications.
"Although this is a valuable tool, we believe these migrations are relatively infrequent (perhaps several times a year)," Roy and Rowe said in their report.
The ESX and GSX server products allow users to partition their Intel servers for the usage of multiple operating systems and applications simultaneously.
"With already about 2 million users and less than $50 million in revenue last year, we can conclude that these products have a low price point," Roy and Rowe said.
But Mark Stahlman, who covers EMC for American Technology Research, feels VMware could prove very valuable for EMC.
He sees what other analysts from companies such as Sageza Research or Gartner see: a company undergoing a metamorphosis as a leading purveyor of storage hardware to a software provider of so-called on-demand, or utility, computing.
Stahlman dismisses the term utility computing as unclear marketing hype, preferring the phrase "virtual computing" to describe a software-driven strategy that configures and reconfigures computing and storage systems with no downtime.
Stahlman told internetnews.com EMC's recent purchases are evidence that the company is trying to improve its position in storage at the same time it is building a broader strategy in virtual computing.
The increased interest in virtualization as a viable computing platform technology is paving the way for an expansion into servers and networks, Stahlman said. IBM (Quote, Chart), and HP (Quote, Chart) already have placement in this arena.
"EMC's benefit from the deal is likely to be an opportunity to integrate its own R&D with the products of VMware as well as gain access to the new company's considerable x86 expertise — crucial now that the Intel architecture is the largest volume for EMC and now that the 64-bit versions of x86 are getting ready to expand rapidly," Stahlman said.
While he wouldn't make any predictions outright, Stahlman said EMC repeatedly referenced network virtualization in a conference call, which he said could be an area EMC is targeting while it digests VMware.
Among the players in the networking virtualization is Inkra Networks. The Fremont, Calif.-based company integrates multiple services, such as firewall, VPN, intrusion detection, SSL, and load balancing in hardware platforms.
Meanwhile, Gartner analysts believe an application monitoring and management or server provisioning company is on tap for EMC. And Sageza Research Director Charles King recently told internetnews.com he expects EMC to acquire database and directory components.
While no one seems to agree on what EMC may buy next, EMC CEO and President Joe Tucci has said his company wasn't actively looking to acquire after VMware. Of course, he said the same thing after announcing the Documentum bid in October.
Linux Journal This article is intended mainly for developers who are new to Xen and who want to know more about it. The first two sections, however, are general and do not deal with code.
The Xen VMM (virtual machine monitor) is an open-source project that is being developed in the computer laboratory of the University of Cambridge, UK. It enables us to create many virtual machines, each of which runs an instance of an operating system.
These guest operating systems can be a patched Linux kernel, version 2.4 or 2.6, or a patched NetBSD/FreeBSD kernel. User applications can run on guest OSes as they are, without any change in code. Sun also is working on a Solaris-on-Xen port.
I have been following the Xen project closely for more than a year. My interest in Xen began after I read about it in the OLS (Ottawa Linux Symposium) 2004 proceedings. It increased after hearing an interesting lecture on the subject at a local UNIX group meeting.Full virtualization has been done with some hardware emulators; one of the popular open-source projects is the Bochs IA-32 Emulator. Another known project is qemu. The disadvantage of hardware emulators is their performance.
The idea behind the Xen Project (para-virtualization) is not new. The performance metrics and the high efficiency it achieves, however, can be seen as a breakthrough. The overhead of running Xen is very small indeed, about 3%.
The community-led project provides an early view of technologies likely to be included in future releases of Red Hat's Enterprise Linux distribution, and is the first concrete evidence that the Raleigh, North Carolina-based company will introduce support for Xen into RHEL.
Created and distributed by XenSource, Xen is an open source virtualization hypervisor that has already received the backing of IBM, Hewlett-Packard, Intel, and Advanced Micro Devices, among others.
Red Hat began talking positively about Xen in October 2004 but until now no concrete plans have been announced. Red Hat's Linux rival, Novell, introduced support for Xen in its SuSE Linux Professional 9.3 consumer product released in April.
Alongside Xen, Fedora Core 4 also provides an early look at OpenOffice.org 2.0, the new version of the open source office productivity applications suite, which is not yet generally available, as well as Evince, a new document viewer for PDF and Postscript files from the Gnome project.
Fedora Core 4 also includes version 2.10 of the Gnome interface, version 3.4 of the KDE interface, version 3.1 of the Eclipse development environment, as well as Red Hat's Global File System integrated clustering technology.
While Red Hat Enterprise Linux has long been available for Power processor-based servers, as well as including 32-bit X86, AMD64 and Intel EM64T, Intel Itanium 2, and IBM S/390 processor systems, Fedora Core 4 is the first Fedora release to also be available on PowerPC. According to the release notes, Fedora Core 4 should boot on Apple Computer's Macintosh PowerPC-based machines.
Earlier this month, Red Hat announced plans to hand over control of its Fedora community-led Linux development project to the new Fedora Foundation, moving Fedora project development work and copyright of contributed code outside of its core business.
An open letter to the current Fedora community from Karen Bennet, Red Hat vice president of applications and tools, indicates that not too much is expected to change. "There are no current plans to change the Fedora Core distribution project, processes, and management," she wrote. "As many have asked, Red Hat will also maintain ultimate overall control of the project to ensure that we continue to have timely, high quality releases."
However, according to Bennet, the Foundation could encourage new projects to develop under the Fedora umbrella without specific Red Hat involvement. "Fedora can only expand by enabling individuals and groups to contribute rather than consume. The Foundation exists to do this, not just for Red Hat originated Fedora projects but for those that come from the community," she said.
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Last modified: March 15, 2008