Overview

Resource utilization. Efficiency. Scalability.Availability. Manageability. Security. These arethe issues that keep data center managersawake late into the night. Virtualization tech-nologies can address these concerns andbenefit the entire enterprise, but they haven’tbeen widely adopted—that is, until recently.

What’s changed? Well, for starters, the datacenter. The number of physical servers hasgrown to unmanageable proportions. Enter-prises need virtualization technologies tocompensate for the inefficiencies of increas-ing server sprawl. Linux* has taken a moreprominent role in enterprises1—handlingeverything from edge services (Web, firewall,DNS and DHCP) to middle-tier applicationand middleware; from backend database, e-mail and file serving to commercial high-performance cluster computing and enter-prise grid deployments. More and moreenterprises are also turning to Linux to helpaddress their multi-tier server consolidationissues. In addition, Intel and AMD havedesigned virtualization functionality into thelatest x86 and x86-64 processors—addinghardware support for server consolidation byenabling strict fault and performance isolation.They’ve also added functionality that enablesunmodified operating systems to run concur-rently on the same physical machine.

In this rapidly changing landscape, Linuxvendors such as Novell have recognized thepossibilities for data center transformation.These organizations are now releasing a newgeneration of products designed to integratevirtual machines—increasing efficiency andmanaging resources in ways that wereunforeseen just a few years ago.

Novell is committed to the propagation of Xen*virtualization technologies. These technologiesare included in the release of SUSE® LinuxEnterprise Server 10, the latest open sourceserver operating system from Novell®. Thisunique opportunity for Novell to take a lead-ing role in the shift to virtualization-based IT is due to the convergence of commodityhardware and open source software—that is,Linux running on x86 and x86-64 computers.It’s a combination that is transforming racksof compute and storage servers into the pre-eminent enterprise IT platform. Virtualizationis also differentiating applications as theyevolve into self-contained modular services.Xen virtual machines take that evolution onegiant step further.

SUSE Linux Enterprise Server 10 and Xenvirtualization technology—coupled with open-standards-based management solutions and identity-driven, directory-based technol-ogies—enable your data center managers to treat all the hardware and software in thedata center as a pool of interchangeableresource components. In effect, the technol-ogy now exists to dynamically bring togetherwhat you need, when you need it, and inways that make sense for your business.

Lose Servers, Gain the Upper Hand

There’s a reason why the typical data centercontains a sea of servers, each running asingle application: isolation minimizes theimpact of crashes. A buggy application run-ning on its own server can only bring itselfdown. A bad fan, a disk failure, or an I/Oproblem will only affect the one applicationthat’s dependent on the defective hardware.Besides, single applications running on ever-more powerful hardware leave nothingto chance regarding headroom. The set-upmay be inefficient, but it works.

So, if you decide to use virtualizationtechnologies to consolidate resources andimprove resource utilization, they must pro-vide the same level of application-workloadisolation, fault isolation and tolerance, andheadroom as the current data center config-uration. In other words, if you have severalvirtual machines (VMs) running on a singlephysical machine, the performance of oneapplication (or lack thereof) must not affectthe others, and administrators must knowthat they won’t come up short with regard toCPU cycles, memory, I/O bandwidth or othernecessary system resources. SUSE LinuxEnterprise Server delivers high-availabilitycomponents that help ensure service levelavailability—even when virtualized—thussatisfying the requirements of the moderndata center environment.

SUSE Linux Enterprise Server 10 running onXen delivers VM isolation for both softwarefaults and varying workloads. By combiningthis VM isolation in a failover cluster thatintegrates commodity hardware, enterprisescan achieve a high level of fault tolerance for hardware failures as well. Furthermore,working hand-in-hand with other softwarefrom Novell and partners, full-scale integrationof virtualization technologies is possible—across physical and virtual servers, SANsand I/O—allowing resources to be pooled,allocated and utilized like never before.

Virtualization Primer

Virtualization refers to the pooling of ITresources in a way that masks the physicalnature and boundaries of those resourcesfrom resource users. In more concrete terms,virtualization is the decoupling of softwarefrom hardware. It is the abstracting of thesoftware from the underlying implementation.(For a more detailed overview, please readthe Novell white paper “Virtualization in theData Center,” located at: www.novell.com/collateral/4622015/4622015.pdf)

With regard to Xen, there are two primaryvirtualization models:

Full Virtualization. In this type of virtualiza-tion, a full platform is emulated by meansof hardware or software—or a combinationof both—in order to support an unmodifiedoperating system. With this method, there’sno need to customize the guest operatingsystem. However, since the operatingsystem was designed to run on physicalhardware, it’s not aware of the VirtualMachine Monitor—also known as the“hypervisor.” As a result, the VM can’tcooperate with other VMs to shareresources and optimize performance.

Paravirtualization. Unlike full virtualization,paravirtualization only partially emulateshardware. The hypervisor is supplementedby APIs that assist in abstracting theunderlying hardware resources to thevirtual machine. Paravirtualization requireshardware-dependent portions of the guestoperating system to be modified to becomeaware of the virtualization layer. Currently,depending on the specific usage case,paravirtualized VMs can outperform fullyvirtualized VMs.

One of the benefits of Xen 3.0, as included inSUSE Linux Enterprise Server 10, is supportfor both paravirtualized and fully virtualizedVMs when the physical server is based onthe latest x86-based processors from Intel*(Intel VT) or AMD* (AMD-V). These proces-sors feature in-silicon virtualization technologythat works with Xen 3.0, giving you a choiceof virtualization models to meet your specific needs .

Xen Rises to the Occasion

Xen 3.0 is a virtual machine monitor (VMM)or hypervisor. It is a software foundation that governs operating systems’ access tocomputer resources, such as memory andnetwork adapters, in order to securely executemultiple VMs—each running its own operatingsystem on a single physical system.

Developed by engineers at the University of Cambridge as an open source project,Xen is the industry’s fastest and most secureserver virtualization software technology. It hasbeen endorsed and adopted by more than20 of the industry’s major vendors, includingAMD, Dell, Hewlett-Packard, IBM, Intel, Novell,Red Hat and Sun Microsystems. BecauseXen technology is open source, it has contin-ued to attract more and more contributors—essentially becoming an open standard. As a result, many companies are now build-ing commercial toolsets for Xen virtualmachine management.

Novell contributes four times more code tothe Xen project than any other Linux vendor.And now, with the release of SUSE LinuxEnterprise Server 10, Novell stakes its claim asthe first enterprise Linux distribution vendorto integrate Xen into the operating system.

With the Xen code and management toolsthat ship as part of SUSE Linux EnterpriseServer 10, you can run multiple operatingsystems on the same physical server withminimal performance impact. As a result,you can significantly increase server utiliza-tion, reduce server sprawl and lower costs.SUSE Linux Enterprise Server 10 and theXen 3.0 virtualization engine afford impres-sive new levels of resource utilization andimprovements in availability, manageability,scalability, performance, application securityand much more.