Analytics Alerts - Virtualization Leaders Get Put to the Test

V i r t u a l i z at i o nLe a d e r s G e tPu t To Th e Te s tWe tested server virtualization gear from five top

vendors to see how they handle strenuous workloads

on a mix of old and new equipment, typical of what’s

found in the wild. The results? Management’s still a

challenge, but any of these products could make your

organization nimbler and more energy-efficient. And

with virtualization upstarts challenging market stalwarts,

you might want to look beyond the familiar names.

A n a l y t i c s A l e r t s

I n f o r m a t i o n W e e k a n a l y t i c s . c o m

M a y 1 1 , 2 0 0 9

2 Where Hype Meets Hypervisors

5 XenServer Means Business

8 Hyper-V Is (Sort Of) Free

11 Parallels And Virtual Iron Look Beyond ‘Big 3’

15 VMware: An Agile 800-Pound Gorilla

18 Still Haven’t Gone Virtual?You’ve Got Company

C o n t e n t s

2 May 11, 2009

R o l l i n g R e v i e w : S e r v e r V i r t u a l i z a t i o n


Where The Hype Meets The HypervisorsBy Joe Hernick

VIRTUALIZATION HAS GONE MAINSTREAM: Business users pull prepackaged corporateVMs over the WAN; college kids rely on VMware Fusion or Parallels to run Windows on theirMacbooks. IT shops recognize the potential operational benefits in large-scale virtualization;CFOs are hoping to get a double win from capital savings and reduced server-farm power bills.But what realities lurk behind the hype?

The question of whether virtual machines are here to stay has been answered; now the ques-tions on IT managers’ tongues are: “What should we virtualize? And which virtualization prod-uct makes sense for us?” Questions of market presence, performance, compatibility, and costget tossed into the mix as well.

If you were talking enterprise server virtualization in 2007, you were talking VMware ESX.What a difference a year makes—VMware is still the market leader for server virtualization, butthe company’s data center dominance is no longer a given. Citrix has aggressively repackagedits sales pitch and business model, metamorphosing from a terminal services and applicationdelivery provider into a full-service virtualization vendor in an incredibly short time. Microsoftintroduced Hyper-V as an integral part of the Windows Server 2008 product line, shaking uppricing models and generating deep thought as purchasing managers assess the ROI on large-scale VM proposals.

Smaller players such as VirtualIron and Parallels further stir the pot, offering full-fledged hypervisor systems that compete with the big three virtualization vendors in niche markets,offering unique products addressing the needs of smaller businesses and non-Windows envi-ronments.

Do the full feature set and mature ecosystem of VMware justify the price tag? Does Hyper-Vaddress the physical-to-virtual consolidation goals of most system admins? Does the opensource flag-waving of Citrix, VirtualIron, and others create a robust hosting environmentthrough “natural selection” and the support of thousands of Xen community members anddevelopers?


Copyright 2009 United Business Media LLC. Important Note: This PDF is provided solely as a reader service. It is not intended for reproduction or public distribution. For article reprints, e-prints and permissions please contact: Wright’s Reprints, 1-877-652-5295 / [email protected].

3 May 11, 2009 © 2009 InformationWeek, Reproduction Prohibited



There’s only one way to answer these questions—a head-to-head Rolling Review using thesame testing methods, and relying on the same business and technical requirements.

PHYSICAL TO VIRTUALWe’ll be starting from the ground up in our test scenarios. We will build four VM hosts, twoidentical higher-end servers reflecting new purchases, and two less-powerful servers represent-ing repurposed equipment freed up as part of our VM server consolidation exercise. All hostswill run a bare-metal hypervisor, with guest VMs and data sets stored on an iSCSI SAN.

The reviews will evaluate each vendor’s ease of setup, configuration, and data and networkconnectivity. Each vendor’s physical-to-virtual conversion tools will be used to migrate real-


IT Server consolidation yields fewer phys- Beware of VM sprawl. Your IT management toolsorganization ical boxes to manage. Virtualization can may not be up to the task for virtual environments

greatly improve operational flexibility, and poor planning can lead to production bottle-freeing IT admins from legacy hardware necks and infrastructure choke points. requirements while simplifying server builds, backups, and restores.

Business Faster prototyping of business applica- VMs operate in shared resource pool pools. If organization tions and more responsive in-house IT the virtualization environment isn’t carefully man-

support are primary organizational ad- aged by the IT organization, errant behavior from vantages. Departments can get serv- resource-intensive VMs on the same host caners more easily, and virtual servers can can affect availability and performance.be repurposed as needed.

Business Fewer physical servers means lower Large-scale virtualized infrastructure deploy- competitiveness equipment costs, reduced energy con- ments can get very expensive. Licensing fees,

sumption, and less stress on HVAC, redundant host servers and infrastructure com-possibly saving on maintenance. Virtu- ponents, and staff training can add up to reducealization pundits praise the “greening” or eliminate a company’s VM business case. of the data center thanks to physical-to-virtual conversions.

Impact Assessment: Server Virtualization

Benefit Risk

Bottom LineEveryone’s doing it; eventually, you will, too. The big question will be what gets virtualized and whenyour shop implements server virtualization. The merits of virtualizing servers are clear; higher utilizationof hardware resources, lower long-term capital expense on infrastructure, and operational flexibility. In-dividual organizations will need to assess their scope of virtualization adoption and implementationstrategies. The cost of implementation, requisite skill sets, and core functionality can vary widelybased on need, desired outcome, and VM vendor platform(s) chosen.




world servers running Windows Server 2000, Windows Server 2003, Windows Server 2008,Windows XP, and Debian Linux into the virtual world. We will clone instances of the resultingVMs to generate up to 10 guest servers per host at maximum load. File servers, LDAP directoryservices, a centralized accounting application, an Apache server, a legacy facilities managementsystem, and a Postgres database will be run on respective guest VMs. Our goal is to reflect atypical physical-to-virtual exercise, where large numbers of low-utilization servers are chosen ascandidates for virtualization. This reflects our experience in the real world as well as the feed-back we get from readers and analysts.

We will balance guest VMs across host servers according to vendor recommendations, imple-menting live-migration capabilities to move VMs from host to host as load and business rulesets dictate. We’ll rate the comparative utility of VMotion vs. XenMotioning vs. Hyper-V’spause-and-move solution.

We also will be implementing ill-advised migration rules and triggers to see how our test sys-tems respond under duress with poor guidelines in place. Simulated user and application loads


THE INVITATION: We looked at server virtualization packages versatile enough to work in a variety of set-tings, capable of scaling as necessary. These products had to be forgiving enough to accommodate IT de-partments’ first virtualization efforts, and robust enough to handle bad parameter sets.

THE TEST BED: We built four VM hosts: two identical higher-end servers, reflecting new purchases; andtwo less-powerful servers that represented repurposed equipment freed up as part of a server consolidationexercise. All hosts ran a bare metal hypervisor, with guest VMs and data sets stored on an iSCSI SAN. Ourtests reflected the host mix likely to be found in the wild, from quad-core HP Opterons with 16 GB of RAM todual-core Dell Xeons running 4 GB.

We evaluated ease of setup, configuration, and data and network connectivity. We used each vendor’s P2Vconversion tools to virtualize servers running Windows Server 2000, Windows Server 2003, WindowsServer 2008, XP, and Debian Linux. We cloned instances of the resulting VMs to generate up to 10 guestservers per host at maximum load. We assessed acceptable loads for different hardware within a single ven-dor platform and compared like tests across different hosting environments.

THE PREMISE: InformationWeek’s Rolling Reviews present a comprehensive look at a hot technologycategory, beginning with analysis and wrapping up with a synopsis of our findings. Our extended testing spanenables InformationWeek to accommodate today’s accelerated revisions cycle and focus our attention on in-dividual products, while maintaining a consistent test bed.

ROLLING REVIEW: SERVER VIRTUALIZATION PLATFORMS

Find out more at www.networkcomputing.com/rollingreviews/




will be automatically generated against each virtualization platform. We will assess acceptableloads for differing hardware resources within a single vendor platform and ultimately comparelike tests across different hosting environments.

Finally, we’ll evaluate bundled management tools for ease of use and functionality, assumingthat users are experienced IT administrators new to the world of virtualization.

WHO’S ON FIRST?Our Rolling Reviews will begin with a test drive of Citrix XenServer, followed by Microsoft’sHyper-V. After we look at a couple of smaller VM hosting solutions, we’ll tackle the marketleader—VMware. We conclude with a comprehensive wrapup detailing the features, perform-ance, and price differences among our participants.

We’ll install the hosting solutions on a variety of hardware platforms. We’ll test hypervisors onservers running chipsets optimized for virtualization from AMD and Intel. Reflecting the mix ofhosts likely to be found in the wild, our test beds will range from Hewlett-Packard quad-coreOpterons with 16 GB of RAM down to dual-core Dell Xeons running 4 GB.

Our test environment will connect via built-in NICs as well as 10 Gigabit Ethernet NICs andswitching gear from SMC, Dell EqualLogic iSCSI storage solutions, and a Dell PS5000XV stor-age array with a 15K storage-attached SCSI drive. Our SAN will consist of SAS arrays to hostour VM guests, and a massive-capacity (up to 45 TB) PS5500E array for our sample data sets.

We anticipate mixed results; our experience shows that different virtual management platformshave different strengths, and there may not be a dominant, one-size-fits-all winner at the end ofthis competition. Stay tuned to see which host makes the most sense for your needs.


Citrix XenServer Means BusinessBy Joe Hernick

CITRIX’S XENSERVER 5.0 ENTERPRISE PROVIDED an impressive start to our server virtu-alization management Rolling Review. This latest version of XenServer offers solid technology,simplified management, and a couple of neat twists that keep the game interesting. After wecompleted this review, Citrix made many of XenServer Enterprise’s critical functions, includingclustering and live migration—available in the free XenServer.





Citrix’s decision to boost the free capabilities in XenServer is a good answer to Microsoft’s “free”Hyper-V offering; while its Essentials for XenServer Enterprise Edition is the next step upCitrix’s product chain.

Larger enterprises will discover that XenServer Enterprise 5.0 does a number of things well. Itmakes virtualization simple and straightforward, bundling XenServer Enterprise as a soup-to-nuts set of products in one box.

XenServer utilizes the Xen 3.2 hypervisor, a native 64-bit virtualization platform written in asvelte 50,000 lines of code with support for Intel VT and AMD-V chipset virtualization assist,and a number of performance enhancements that target Microsoft operating systems.

Initial installation and setup of Xen uses simple, menu-driven fields for the entry of environ-ment parameters such as host name, license keys, IP addressing information, and permittingSSH access. We also used the basic interface to connect our first two hosts to our SAN. All con-figuration and management functionality can be accessed from the command-line interface orvia system menus, but most admins will fire up the XenCenter GUI management tool as soonas the first host is created. Linux CLI-shy Windows admins will feel right at home inXenCenter.

XenCenter let us create resource pools and assign XenServer hosts to those pools. And here’swhat we liked most: Citrix has implemented a Clustered Management Layer. That means nomore dedicated, single-point-of-failure management server; any host in a resource pool can bepromoted to the role of XenCenter host. Copies of system information, performance data, andlogs are distributed across member servers. This greatly increases the utility of the high-avail-ability feature set.

XenCenter offers quick access to a console view, storage assignments, network, performance,logs, and general information. Admins can create custom data fields and tags for individual vir-tual machines; tagging is a drop-down item under the General tab. This is useful as your VMcount rises, giving admins flexibility in searching, sorting, or modifying VMs based on site-driven custom terms.

Using resource pools or virtual machine host tools, local storage and network settings can bedeployed to all running VMs.

Physical-to-virtual (P2V) migration caused a hiccup on our 64-bit Windows 2003 app serverbecause of, well, user error. After reading the manual, we realized that having a large scratch vol-




ume (an empty volume) is a good plan, and auto-mount must be enabled for the P2V conver-sion to complete. Auto-mount enabeles the Xen virtual hard drive-formatted virtual disk to berecognized by the operating system so the converter can write the disk image and finish the job.

The wizard-driven P2V tool, XenConvert, provides solid error logging. The P2V conversionruns with no need to reboot; XenConvert creates a point-in-time snapshot of a running pro-duction server.

EVERYONE INTO THE POOLXenServer Enterprise and Platinum allow admins to create load-balanced resource pools of Xenhosts. Shared storage repositories allow for live migration—XenMotioning in Citrix-speak, ver-sus VMware’s VMotioning—where running VMs can shift from host to host as productionneeds or operating requirements change.

XenCenter balances virtual machines across all available hosts based on processor and memoryresources, and it assigns newly created VMs as needed. VMs may use a single host’s local stor-age, but a “local” VM would need to be powered down and manually relocated to switch hosts.XenServer will run on older hardware lacking virtualization support (e.g., pre-Intel VT orAMD-V chipsets), but you won’t be able to run Windows VM guests, nor can you join the hostto a Windows-aware resource pool.

XenServer’s storage integration and management reveal a touch of elegance: Recognizing thatcustomers have paid good money for advanced storage features, XenServer capitalizes on hard-ware-assisted snapshots, cloning, and replication options from a variety of vendors.

Storage Delivery Services works with NetApp and EqualLogic arrays, integrating with vendorAPIs to perform cloning and to take snapshots of virtual disks using the arrays’ native featuresets. This reduces CPU loads on hosts and decreases the time that’s required for disk-intensivemaintenance.

HIGH AVAILABILITYOne of the most significant enhancements in this revision is the bundled automated high-avail-ability feature, with which XenCenter can dynamically reallocate running VMs in the event of ahost failure. Once high availability has been configured for a pool of XenServers, the group canabsorb host failures with minimal downtime for running VMs. Setup is straightforward. If ahigh-availability-enabled host goes down because of hardware failure, power outage, or othererror, XenCenter will assess current resource availability across the remaining host server pooland restart orphaned VMs.





Citrix also integrates XenCenter and high availability. While the management console resideson a primary Xen host, the latest version utilizes a distributed architecture so that any host in aresource pool can grab the management baton and keep running. We really appreciated thedistributed nature of the management console. High availability wasn’t instantaneous in tests,but the minimal outage window and ease of use will make it a winner for many installations.

And there shouldn’t be much quibbling over the price. The Express version of XenServer isfree, although it’s limited to single host server management viaXenCenter and doesn’t provide resource pools or migration capa-bilities.

The $780 XenServer Standard allows multiserver management.XenServer Enterprise, which we tested, offers live migration, hostresource, and storage at $2,600. XenServer Platinum adds dynamicworkload provisioning of physical and virtual servers and requiresan Enterprise license, plus licensing for Citrix Provisioning Server,for an additional $2,000. Citrix’s Subscription Advantage supportplan costs extra.


> XenServer provides ease ofsetup, a maturing managementinterface, and a decent set oftools for budget-strapped times.

> Larger corporate buyers mayopt for VMware’s broader base ofthird-party support, but XenServ-er's pricing will appeal to many.

> We like XenServer’s distributedmanagement tools and high-availability options.

Our Take[

Microsoft’s Hyper-V Is (Sort Of) FreeBy Joe Hernick

WINDOWS-ONLY SHOPS LOOKING TO DO A LITTLE virtualization on the cheap needlook no further than Microsoft’s Hyper-V and the freebie Hyper-V Server 2008 standalone host.However, our tests showed that customers with even mildly complex virtualization require-ments should run Hyper-V on top of Enterprise or Datacenter editions of Windows Server2008 and manage guest virtual machines by adding System Center Virtual Machine Manager—which brings on licensing costs.

As for non-Windows environments, Microsoft’s claim that Hyper-V is capable of mixed operat-


R o l l i n g R e i v e w : S e r v e r V i r t u a l i z a t i o n



ing system virtualization is technically accurate, but the latest version of Novell’s SUSEEnterprise is the only flavor of Linux supported across the Hyper-V range.

This leaves Red Hat, Debian, and other Linux variants to run on other hosts, such as Xen,KVM, and VMware. Linux-heavy organizations that aren’t using SUSE Enterprise should bypassHyper-V in favor of VMware ESX, Citrix XenServer 5.0, or another alternative.

The elephant in the room is Hyper-V’s lack of live migration support; VMware and Citrix allowa running virtual machine to shift from host to host with no production outage. But despiteearly promises to the contrary, Hyper-V doesn’t allow live migration.

WELL-BEHAVED GUESTSIf these issues don’t apply to you, Hyper-V has a couple of selling points beyond the price tag.Windows guest virtual machine performance was more than satisfactory on both our trimmed-down Hyper-V Server 2008 test setup and our “fat OS” installation of Hyper-V on WindowsServer 2008 Enterprise.

Microsoft also offers a sensible license model that simplifies management for midsize and largercompanies using Windows Server 2008 Datacenter. Datacenter removes Windows guest VMlicensing compliance headaches by permitting one physical server (the VM host) and unlimitedguest OS instances under the same umbrella license. Citrix and VMware, in contrast, can’t offerblanket licensing for Microsoft guests. Windows Server 2008 Enterprise versions allow for ahost server plus four VM licenses.

At the other end of the spectrum, a Server 2008 Standard Edition license includes the host plusone guest; additional guests must each get their own license codes. And although Hyper-VServer is free, organizations are responsible for individual licenses for all hosted Windows vir-tual machines. We had no setup or installation issues adding Hyper-V services to our new orexisting Windows Server 2008 hosts. Hyper-V Server 2008 ran well on our virtualization-awarechipsets from Intel and AMD, although each server in our test environment required a baseinstallation of Windows Server 2008 and attendant updates prior to revving up Hyper-V.

Hyper-V proved to be a worthy host on our test setup, a four-host Windows 2008 clusteraccessing a shared EqualLogic iSCSI SAN. We had to install Microsoft’s System Center VirtualMachine Manager (SC-VMM) 2008 to match the management tool functionality in other hostplatforms in this Rolling Review. With Hyper-V essentially free, the $869 SC-VMM unlimitedlicense or $505 five-host license are relative bargains for Microsoft customers.

Tapping SC-VMM’s “intelligent placement,” Hyper-V does a capable job of allocating new virtu-al machines to physical servers, comparable to XenCenter’s virtual machine placement.

SC-VMM’s physical-to-virtual conversions virtualized existing Windows servers without a hitchin our tests. Physical-to-virtual conversions of XP, Windows 2003, and newer Microsoft operat-ing systems utilize Volume Shadow Copy Service. Like XenConvert or VMware Converter, SC-VMM physical-to-virtual migrations can grab a snapshot of a running production machine.

One of the interesting things we discovered during tests is this: You can’t overcommit physicalmemory resources for guests in a standalone Hyper-V environment. Hyper-V instead talliesallocated memory for all local guests, whether they’re running or not, erring on the side ofcaution. In contrast, VMware gives administrators the option of overprovisioning systemresources on single hosts, on the assumption that all host virtual machines in a system won’tneed to run maximum resources simultaneously.

Although we don’t advocate overextending your hardware, this is a useful capability forreallocating resources in emergencies. For example, if your virtual server environment hasfour host servers, and one dies, overcommitting enables your setup to temporarily run fourhosts’ worth of virtual machines on three hosts.

NOT-SO-LIVE MIGRATION VMware has VMotion and Citrix has XenMotion, both of which provide for live migration ofvirtual machines. Microsoft, on the other hand, has Quick Migration,which isn’t live and is slower than VMotion or XenMotion. Despite earlyfeature-set promises, Hyper-V doesn’t support true live migration of a vir-tual machine from one physical host to another on any version of Win-dows Server 2008. Instead, the Microsoft Quick Migration feature allowsa centrally stored VM to be suspended or shut down, then restarted on anew host.

The consensus is that Microsoft opted for Quick Migration to get Hyper-V to market as soon as possible while satisfying basic functionality needsand enabling clustering and high-availability options for Win2008Enterprise and Datacenter customers as a bundled perk.

Whatever the corporate strategy, no live migration means little or noservice or maintenance on Hyper-V hosts during business hours—someHyper-V admins will need to put in time during off-hours to handle





> Hyper-V is best for virtualizationnovices in small shops orWindows-only environments

> It’s hard to argue with free,but overall, Hyper-V feels like a“me-too” product, released soMicrosoft would have a modernvirtualization offering on themarket

> Rival products cost more, butyou don’t have to spend extra toget broad Linux support and livemigration

Our Take[





these chores. This will make Hyper-V a nonstarter for many shops, leading them toward Xen orVMware.

Quick Migration times can range from seconds to minutes for restoration of all services in acomplex environment—you must take a server VM offline to move it to a second machine withHyper-V. If you have ungainly apps or complex environments, they’ll take awhile to get rolling.We expect some version of live migration in future releases of Hyper-V, so prospective hypervi-sor customers and vendors should keep an eye out. But for the time being, the bottom line isWindows’ low cost and familiarity versus competitors’ industrial strength and convenience.

Hyper-V’s high availability is less of a pain point than its hobbled VM migration functionality.As with the latest version of XenServer Enterprise, Windows Server 2008 running Hyper-Vbundles high-availability functionality for clustered hosts. And since clustering is now bundledwith 2008 Enterprise and Datacenter, cost isn’t an issue.When we conducted our “yank out thepower” test, Hyper-V came through with flying colors, restarting guests on other cluster hostswith minimal disruption. It isn’t an instantaneous failover, but the minimal outage window ismore than acceptable, given the product’s zero cost.

Parallels, Virtual Iron Make Their CasesBy Joe Hernick

IT’S EASY TO FOCUS ON VIRTUALIZATION’S “BIG THREE”—VMware ESX, MicrosoftHyper-V, and Citrix Xen—because of their combined dominant market share and pervasivemarketing. But there are other players entering the fray that are worthy of recognition. So forthis segment of our Rolling Review, we brought a couple of less-well-known virtualization plat-forms, Virtual Iron Extended Enterprise Edition 4.5 and Parallels Server for Mac 3.0, into ourtest lab.

These two smaller players show there’s more than one way to run virtualization hosts: VirtualIron ably jumps through some of the same hoops as XenServer and Hyper-V, and we believe itcould challenge VMware ESX in larger enterprises, if the company wanted to.

Although Parallels Server wasn’t up to our full gamut of tests, being a slightly different beast, itdoes serve its niche well, running Windows, Linux, and Mac OS X Server instances on Applehardware.





In terms of performance, every server virtualization product we’ve tested so far in this RollingReview has done more than live up to the vendors’ claims, showing rapid evolution as the mar-ket has heated up. Virtual Iron’s and Parallels Server’s application performance also pleasantlysurprised us.

Like the Xen-based virtualization system from Citrix, Virtual Iron has revved up its perform-ance over the last few years while dramatically easing installation and administration tasks.Parallels leverages its “fat OS” experience with Parallels Desktop to deliver solid performancefrom its hypervisor, despite the underlying requirement of a full-load Leopard 10.5 OS chew-ing up system resources and routing I/O.

Both platforms are aimed squarely at the small- to midsize-business sector. Virtual Iron devotesmost of its marketing to this segment, although we could see Virtual Iron 4.3’s Xen-basedhypervisor, centralized management, and per-socket pricing model playing well in larger com-panies, too.

Parallels Server isn’t as mature or feature-rich as Virtual Iron. Its limited storage options, sim-plified networking capabilities, and lack of migration tools mean Parallels Server likely will becrossed off most potential customers’ short lists, unless they’re Mac shops. VMware’s Fusion istinkering with Mac OS guest support, but Parallels Server currently is the only solution on themarket that lets you virtualize Apple Server instances with Apple’s blessing.

FIND YOUR VI-CENTER

We built our Virtual Iron environment in an SMB frame of mind, and encountered no snags.Installation is simple; no archive file or boot disks here—Virtual Iron relies on VI-Center, aJava-based central management and network distribution tool, to get things moving. The con-sole can be installed on any Windows Server (2003 is recommended) or Linux host. No fancyhardware is required, so this is a great way to repurpose an older server for new life. Weinstalled VI-Center GUI on Windows 2003 and 2008 servers. After turning off Windows 2008’ssecurity nannies and downloading the latest Java runtimes, we were ready to virtualize in about10 minutes.

The last time we ran VI-Center through the lab (in its version 3.1 days), Fibre Channel was theonly way to build a storage area network. Support for iSCSI is a welcome addition in VirtualIron 4.5. On startup, all hosts show up in the VI-Center graphical user interface as availablehardware resources. The VI-Center server makes short work of configuring networks, networkinterface cards, local and iSCSI disk groups, SANs, and virtual NICs.




Windows admins who are virtual machinery rookies can walk step by step through VirtualIron’s sidebar tutorial, all the way through building and assigning VMs to hosts.

Console views worked just fine in tests, although Linux control wasn’t as smooth as Windowsguests in our tests. Guest performance was more than satisfactory, however.

Virtual Iron’s live virtual machine migration is dubbed LiveMigrate. LiveMigrate touts hardwareindependence, but according to the manual, make sure you go Intel-to-Intel or AMD-to-AMDwhen migrating. VI-Center does a good job of vetting the target host to ensure that memory,processor, and access permissions to the resource pool are all in place before allowing a move.It therefore can save you from bad decisions by simply not permitting a forced move to a hostrunning at full capacity.

Like VMware, Virtual Iron prices per socket, delivering more bang for the buck with quad-coreover dual-core chipsets. Of course, $799 per socket is significantly less than VMware ESX pric-ing, especially since Virtual Iron is following Citrix’s model of bundled management tools. Interms of list price, going with Virtual Iron instead of VMware yields savings of 50% or more.

Physical-to-virtual and virtual-to-virtual conversions happen thanks to partner PlateSpin. Theincluded bundle grants six conversions per socket license, which should take care of most con-solidation scenarios. Additional conversion licenses can be purchased from PlateSpin.

PARALLELS’ LINE

As of this writing, Parallels Server is the only game in town with production support for host-ing Mac OS X 10.5 Server guests. However, VMware’s Fusion, Sun’s xVM, and other majormarket forces are closing in, pushing Parallels to stay on top of its game.

As an aside, we like Parallels’ desktop virtualization offering, Parallels Desktop 4.0 for Mac. Thelatest revision resolves several usability and performance issues. Unfortunately, the current ver-sion of Parallels Server, 3.0, shares a version number with the last generation of Desktop.

Parallels Server brings a world of flexibility to Apple’s Xserve line. Mac developers and produc-tion shops are already utilizing Parallels for test and sandbox environments; the novelty of vir-tualizing OS X builds seems to supersede the limited feature set compared with other hypervi-sor platforms.

Mac-only IT shops will probably be pleased that the product allows them to consolidate multi-





ple out-of-support Wintel and Mac G4/G5 servers onto one or two new Xserves.

Parallels performed well on Apple’s top-of-the-line eight-core Harpertown Xserve with 32 GBof RAM, three 15,000-rpm SAS drives and a Fibre Channel connection to a legacy AppleXserve RAID setup with 4 TB of usable storage. In addition, we tested an older dual-core, 8-GBXserve. Intel VT-x is required, which means older 64-bit PowerPC Xserves can’t run Parallels.

Parallels was a gracious host for Windows 2003 and 2008, Debian, and OS X Server guestswith no issues. Guest performance was more than adequate on the Harpertown box, while ourolder Xserve faced resource constraints when asked to run three Windows 2003 instances.Apple doesn’t provide iSCSI support in OS X, but a number of hardware and software vendorsoffer third-party products.

The strangest issue we encountered involved USB support for a Windows 2003 guest—a low-use server ripe for virtualization (in this case, a building management system) that required anold-school USB dongle to function. Parallels Server does not offer USB support or robust virtu-al LAN mapping for guests VMs.

Multiple virtual Parallels Servers can be managed from the Parallels Management Console. Likeother virtual machine management GUIs, hosts and guests can be paused, suspended, stopped,and reconfigured. Individual VMs can be accessed via detach-able consoles. A stopped VM can be cloned.

However, there’s no snapshot functionality, and performanceprioritization is limited to optimization for either host or VM;there’s no weighting between guests. There’s also no live migra-tion capability: VMs must be shut down and manually movedto a new host.

Parallels Transporter, the bundled physical-to-virtual conver-sion tool, performed with no issues in our tests.

Parallels charges just under $1,250 per host server regardless ofconfiguration. This price is ideally suited for maximizing aneight-way Xeon Xserve, although it’s not necessarily cost-effec-tive for squeezing extra oomph out of a 2006 dual-core Xserve.


OurTake

PARALLELS SERVERFOR MAC 3.0 AND VIRTUAL IRON 4.5 [

> Small and midsize businesses look-ing for an easy, economical path to vir-tualization, or Mac shops hoping todump Windows hardware, will findthat Virtual Iron and Parallels Server,respectively, fit the bill nicely.

> Parallels Server enables Mac OS Xserver virtualization without breakingany of Apple’s rules. It hasn’t receivedthe same attention to detail as ParallelsDesktop, though, and it shows.

> Virtual Iron could go head-to-headwith VMware in the data center, but it’sbuilding its base from below with aneasy-to-administer product at a veryaggressive price.





VMware: An Agile 800-Pound GorillaBy Joe Hernick

VMWARE INFRASTRUCTURE 3.5, the 800-pound gorilla in our Rolling Review of hypervi-sors, continues to lead the virtualization pack in performance, support, and scalability. In tests,the VMware Infrastructure suite—comprising the VMware ESX hypervisor, vCenter Server, andclient tools—got our virtualization job done handily. But whether it’s worth the premium pricemay be another matter.

Version 3.5 answers some calls for easier setup and management features. For example,VMware offers Guided Consolidation, an easy-to-use analysis tool for virtualizing Windowsenvironments, along with new patch management capabilities and enterprise-class support. Inaddition, the VMware ecosystem offers thousands of ready-to-roll virtual appliances, and APItie-ins and vendor partnerships provide limitless management, reporting, automation, storage,and security options.

VMware also has the most difficult learning curve for novice admins and the highest price tagamong the participants in this Rolling Review. Does this sound like a winning combo to you?

Citrix Systems promises that you’ll only need a few minutes to achieve Xen, and we had ourbase Virtual Iron, Parallels, and Hyper-V test platforms up in less than an hour. Our virtualiza-tion-neophyte experience wasn’t as smooth with VMware. Yes, ESX 3.5 did everything weasked of it for our small-business model test case—and more—but it took the better part of aday to get our base environment up and running. This was a “real world” test, using IT admintest subjects who have limited familiarity with virtualization and no familiarity with VMware.This is in line with many small IT shops, working under constricted budgets, with limitedtraining options and cranky CFOs, faced with aging hardware and flat staffing models.

For shops still running VMware ESX 3.0, the incremental upgrade to 3.5 makes sense for theadded management features and VirtualCenter improvements. New customers looking to gettheir feet wet can check out the 60-day free, full-featured trial to assess and experiment withphysical to virtual conversions, consolidation modeling, and plain old-fashioned comfort andease of daily use. Then again, all vendors in this Rolling Review offer some form of free demo.During the course of our testing, the price points changed for some participants, and additionaltechnology and improvements have been introduced.

To be clear, VMware is well worth a look. The planning tools are unmatched, and the potentialfor patch management and green computing options can make the high price worth it formany. The product just took a bit more head-scratching and manual-reading for initial setupthan the competition.

We brought a Windows administrator with minimal virtualization experience into the virtual-ization test lab to help us get a newbie’s perspective on the physical-to-virtual scenario. Thebest quote from our VMware experience? “Whaddaya mean I need an Oracle database? Oh—SQL will work? Great. So here we go, setting up a SQL 2005 server to manage our VMwareenvironment. This is what I need to use to get a global view, right?”

Right.

Setting up a single ESX 3.5 host managed by the standard VM Infrastructure Client tool wasfairly painless. Unless you want to access iSCSI storage, that is. Or tinker with the many robustnetworking or configuration options.

Whereas other vendors in this Rolling Review address storage area networking during basicsetup, the default ESX install assumes local storage. Configuring iSCSI, setting VMKernal inter-faces, selecting network interface cards for data access, picking a SAN target, and setting updata stores took many, many steps. Setup was made possible using VMware InfrastructureClient’s built-in help, but it was laborious compared with most competitors’ iSCSI out of thegate.

We built four ESX hosts on virtualization-enabled HP multicore Advanced Micro Devicesservers. Everything was connected to our Dell EqualLogic 5000-series SAS and iSCSI arrays. Aswe’ve said before, having many platters across 48-TB drives is great for I/O and fantastic forvirtualization clusters. Sixteen 15,000-rpm drives in the SAS array also made quick work ofstorage tasks; for our money and for most small shops, we’d consider the higher capacity of theSerial ATA. After a hiccup attempting to install Virtual Center and its requisite MS SQL 2005on a 64-bit Windows 2003 box, we easily set up a spare Windows XP workstation as our man-agement host. Data and SAN connections were physically divided to two Cisco GigabitEthernet switches, and everything was first run on a closed network for base testing, thenopened up to a 400-user public network to get some real-world experience.









We configured individual hosts with both Infrastructure Client utility and Virtual Center.Within VirtualCenter, we created a test cluster with our four physical hosts and played aroundwith manually shuffling virtual machines from host to host with VMotion. Even though we’vebeen doing this for a bit, we still smile when we watch a running, CPU-loaded Windows 2003VM hop from host to host in a matter of seconds without dropping a beat (or a ping). We usedthe VirtualCenter to create a resource pool so that we could conceptually view and manage ourfour servers as an aggregate pool of CPU and memory resources.

We have no complaints with performance; we were very impressed with 32-bit Linux and 32-and 64-bit Windows performance in our small-business tests. We readily built clusters ofshared resources relying on the SAN for centralized storage. After the painless installation ofVMware client tools, cloning, snapshots, and VMotion flexibility all met or exceeded our easeof use and performance expectations when compared with real-world physical servers; you’redoing yourself a disservice if your shop rejects virtualization out of hand.

Our EqualLogic SAN goes one step farther, offloading snapshot tasks to the storage array—thisis the first chance we’ve had to test this out. Offloading snapshots to the SAN hardware savesCPU resources in the host cluster. This is another example of a benefit from VMware’s place asfront-runner: New features from third-party vendors in the virtualization arena come out forthe VMware ecosystem first, then broaden support to include othervendors.

To dig further into our small-business simulation, we virtualizedreal-world Windows servers using Virtual Center’s GuidedConsolidation tool. While the provided recommendations were fair-ly straightforward, the real benefit of VMware’s Active Directoryintegration would shine in a larger data center environment, wherethe tool continually probes and monitors physical Windows serversas candidates for conversion.

Once converted, the automated rule sets assigned VMs to hostswithout issue. A big, shiny consolidation button sits on the VirtualCenter 2.5 interface, offering suggestions and impact analysis forvirtualizing physical boxes in your shop. As we added VMs or pur-posefully “mismanaged” our test farm, Virtual Center soundly adapt-

> VMware’s a la carte menu ofofferings may be good for largerenterprises, but could confusesmaller shops or new customers.

> VMware’s long track recordmeans there’s a huge supportedOS list, lots of VMware-trained ex-perts, broad third-party support,and thousands of canned virtualappliances ready to go.

> Competitors bundle manage-ment tools or offer the whole dealgratis.

Our Take[

ed to changing loads and existing rule sets and VMotioned us out of harm’s way. Everythingworked as planned.

On a final note, automated patch management left us with smiles all around. After a somewhatbyzantine process of configuring VirtualCenter to add the Update Manager component andclient plug-in, we set up automated patching for ESX hosts and Windows VMs using UpdateManager. We followed VMware’s recommendation and set up a three-hour interval to check forupdates. After selecting security patches for application, we picked an idle host for updates. Wealso readily applied Windows security patches to specific VMs and had comfort knowing wecould easily roll back to pre-patch snapshots. This isn’t a magic bullet for all data center patchrequirements, but it is a nice plus from VMware and is a clear example of how virtualizationcan reduce administrative burdens.

VMware ESX 3.5 starts at a base price of $1,540 for two processors, Distributed ResourceScheduler starts at $2,414, and the VMotion/Storage VMotion combo starts at $4,024. VCenterServer Foundation starts at $2,040 for three physical hosts and ranges up to $6,044 andbeyond to manage hundreds of hosts. Various bundles and a la carte options also are offered.





Virtual Market Shifts Into Higher Gear By Joe Hernick

VIRTUALIZATION HAS EMERGED from the obscurity of the test lab and developmentworkstation to mainstream production and beyond. The benefits are real, and some companiesalready are testing the next tier of virtualization performance. If you’re like many IT shops—particularly IT shops in smaller companies—you probably feel behind the times when it comesto adopting data center virtualization.

The real news is, you’re not. A recent InformationWeek survey of 348 business technology prosshowed that roughly 47% of organizations with fewer than 1,000 employees had not yet virtu-alized. Roughly 23% of these facilities were planning deployments. Furthermore, interviewswith IT managers from smaller shops show anecdotally that small and midsize businesses arejust starting on the physical-to-virtual conversion path.




Like their larger-business counterparts, smaller IT shops are wary of placing multiple criticalsystems on one host, and with good reason. Consolidating a number of legacy servers onto asingle Microsoft Hyper-V or VMware ESXi host may make short-term financial sense, but italso introduces single-system points of failure for all guests residing on that host. Concernsabout deployment, management, capacity planning, and production outages haven’t been leftbehind with the 20th century.

Good planning can mitigate concerns about putting all eggs in one virtualized basket. Anappropriately sized, robust, centralized storage system; three or more host servers; and a bit ofredundant networking often yield a more resilient environment than many smaller shops have.When existing servers and gear can be repurposed to VM host platforms, the cost/benefit num-bers look even better. Add an inexpensive—or free—hypervisor, live migration, and basic man-agement tools, and the business case begins to write itself. Tasks that are arduous in the physi-cal world become routine in virtualized space; capacity planning, patch management, highavailability, and disaster recovery are much simpler to master once servers make the physical-to-virtual move.

Armed with the belief that virtualization technology is both ready for prime time and appropri-ately complex for nonexpert deployment, we tested major and minor players in the hypervisorarena. For this Rolling Review, we set up our test bed as if we were a small IT shop looking toconsolidate workflow and migrate from older physical servers to the virtual world. We assumed


Real-World Analyst Assessment Server virtualization

Xen

Srv

t

Hyp

er-V

Para

llels

Virt.

Iron

VMw

are

Shortlist 4 , Editor’s Choice P , Best Value $ 4 $ 4 P

Ease of installation

Day-in/day-out management

Enterprise functionality

Windows VM performance

“Bundled” price

Bottom Line: VMware, Citrix, Virtual Iron, and Hyper-V met or exceeded our expectations for running an SMB servershop. Parallels Server doesn’t measure up to the others in features or performance, but it’s the only Apple-sanctioned Macserver virtualization management platform.

UNACCEPTABLE IDEAL




that administrators would be familiar with Windows server management and generally comfort-able with basic Linux administration. We also brought in IT admins with limited virtualizationexperience to get a fresh perspective on the platforms tested.

We were pleasantly surprised every step of the way. In tests, virtual machine performance occa-


Straight hypervisor performance doesn’t reflect the en-tire cluster management-performance experience.This Rolling Review was, first and foremost, a qualita-tive assessment, so we built our test bed to gauge

each product’s setup, physical-to-virtual conversions, and day-to-day manageability.

We ran all five platforms on a variety of server hardware,then put all of the virtualization suites except Parallelsthrough a final series of tests on identical hardware. The testcluster included four quad-core Hewlett-Packard DL385-G2servers, two configured with 12 GB of RAM and two config-ured with 8 GB of RAM.Within each, host hypervisors were in-stalled on a pair of hardware-RAID mirrored 72-GB 10,000-rpm SAS drives. VMware, Citrix, and Virtual Iron installationswere bare metal, and Microsoft Hyper-V was installed on topof Windows 2008.

All hosts were connected via Cisco’s 3750G for iSCSI SANaccess to Dell EqualLogic PS5000-series SAS and SATA stor-age devices. We base-tested connectivity with legacy FibreChannel storage arrays to verify functionality, while a 16-driveSAS array and 48-drive SATA array allowed us to test compat-ibility and performance reflecting commodity solutions. TheDell system was very easy to set up, configure, and maintainthroughout testing. Small and midsize businesses would dowell to investigate entry-level, expandable iSCSI SANs fromDell or other vendors. We formatted the 48 TB of raw storageas one 32.3-TB RAID-50 pool, from which we sliced out 5-TBresource pools for each virtual machine cluster.

Each host had one dedicated gigabit network interfacecard for iSCSI traffic, and the 3750G was dedicated to storageonly; no other communications traversed the physically iso-lated switch. All Ethernet data connections for the VM clus-ters ran over a second 3750G, with one gigabit NIC per hostfor network communications and one gigabit NIC for VM

management. Three virtual LANs separated network traffic:one subnet for VM management and two subnets for VMtesting.

All servers were rolled into four-host VM clusters for thefour mainstream hypervisors, yielding a virtual pool of re-sources encompassing 16 2.6-GHz cores, 40 GB of RAM, and 5TB of storage on the storage area network. It’s easy to see whyold-school mainframe wonks smile whenever 20-somethingIT admins get excited about virtualization.

We tested Parallels Server on four- and eight-core AppleXserves running 8 GB and 32 GB, respectively, with the hyper-visor installed atop Mac OS X Server 10.5.5 on hardware-RAIDmirrored 80-GB SAS drives. Apple doesn’t officially supportiSCSI connections, only Fibre Channel SANs. We tested Paral-lels with a legacy Fibre Channel storage device and local stor-age. To guarantee support from Apple and Parallels, we rec-ommend sticking to the Fibre Channel SANs on Apple’s shortvendor list for any Parallels Server installation.

We chose a Windows 2003 host running on older, nonvirtu-alization-optimized hardware as our physical-to-virtualguinea pig. During the course of this Rolling Review, we vir-tualized many varieties of Windows and Linux with decent re-sults. For the wrap-up, we stuck with simple 32-bit Windowsserver conversions on the assumption that most SMBs initiallyconsolidate older legacy servers to get aging hardware of-fline.The host ran file services serving up local storage, IIS forbasic static pages, and DNS. Each vendor’s (or vendor’s part-ner’s) physical-to-virtual converter worked without issue, cap-turing the Windows 2003 host as a VM.

We installed each vendor’s virtualization tools to optimizedrivers for video and system performance, then took snap-shots of the completed base images.Then we cloned the heckout of our images to populate our clusters with Windows andDebian VMs, and ran with the ball. ——JJooee HHeerrnniicckk

HOW WE TESTED A GAUNTLET OF OLD AND NEW GEAR




sionally exceeded the premigration results of older physical servers. With planning, we couldconsolidate dozens of low-utilization VMs across our four older boxes. And once the cluster ofvirtualization hosts and centralized storage was up and running, we found the day-to-day careand feeding of virtualized servers was much less of a hassle than the drudgery of riding herdon traditional physical servers.

EVERYONE’S A WINNERVMware, Citrix, Virtual Iron, and Microsoft met or exceeded our expectations for running anSMB server shop. Any of these could ably handle VM chores in a smaller organization. Thebiggest differences among them are in pricing and third-party support.

VMware, Citrix, and Virtual Iron will handle Windows and Linux consolidation efforts andaccommodate future plans. Each provides physical-to-virtual conversion, broad OS support,centralized management, and solid performance. VMware, Citrix, and Virtual Iron offer the abili-ty to live migrate running virtual machines between hosts in the same cluster—a key ability.

Our fifth Rolling Review entry, Parallels Server for Mac 3.0, couldn’t match the other four prod-ucts we tested in terms of performance or features. But Parallels is the only game in town forvirtualizing Mac servers (at least officially), and did an adequate job in our tests.

So how do these platforms stack up? Here’s our final tally:

>> If we were running a small or medium-sized IT shop with a modest staff, hoping for six-to-one or eight-to-one server consolidation, we’d strongly consider Citrix Xen. Recent changes inCitrix’s pricing models make it even more appealing. XenServer Enterprise, at $2,600 per serv-er when we tested it, seemed like a good deal. Since then, however, most of XenServer Enter-prise’s critical functions—clustering with decentralized management and live migration—havebeen made available in the free XenServer.

This means Citrix is now pushing lots of functionality out the door for free in XenServer, whileoffering Essentials for XenServer Enterprise Edition as the next step up the product chain.Essentials offers storage management, historical reporting, and high availability, along withother features, for $2,750 per server, or $11,000 for our four-host cluster.

>> Microsoft’s Hyper-V is tough to beat on price or Windows performance; most enterpriseswill receive Hyper-V as part of their annual Windows server support subscription, bundledwith Windows 2008. Windows network administrators will be most comfortable and will needto travel the least distance to get a Hyper-V farm up and running. However, Linux-heavy shops





will need an additional virtualization option to get off the ground, and Red Hat, Debian, andother Linux variants beyond the supported SUSE will need to get their virtualization else-where.

Live migration was the deal breaker for us: Microsoft offers Quick Migration, and that’s notlive migration. Microsoft recently announced that live migration will make its way into Hyper-V Server 2008 Release 2, but today’s system requires admins to take VMs offline when migrat-ing to a new host. R2 is slated for release sometime next year.

We managed our Hyper-V cluster with Microsoft’s System Center Virtual Machine Manager2008, $869 for an unlimited server license. We’ll grant Hyper-V its “free” claim because mostcustomers considering it already will have licenses on hand.


Want to fight global warming? Try virtualization.The biggest marketing trumpet for virtualiza-tion has been monetary savings—physical-to-virtual conversions reduce capital expense by

consolidating many servers onto fewer hosts. Additional po-tential savings can come from reduced management costs,less downtime, and lighter staffing.

As energy prices have fluctuated widely during the pastyear, CFOs are punching new holes to tighten corporate beltsever further, looking for savings wherever they can. Powerand heating and cooling costs are surfacing as areas of op-portunity.

That’s all good for a company’s bottom line. But in additionto freeing up floor and rack space, large-scale server virtualiza-tion can result in significant reductions in electrical and cool-ing needs. And since most of our power comes from burningfossil fuels, it’s safe to say that each server is responsible fortons of carbon dioxide annually. General assessments are 4 to12 tons of CO2 per server per year.

Are swimming polar bears starting to haunt you yet?The stats associated with virtualization vary widely, de-

pending on who’s making the pitch. For example, Oriel Tech-nologies, an Australian VMware channel partner, proposesthat paring 45 servers down to five host servers through virtu-

alization can keep 506 tons of carbon dioxide out of the at-mosphere. I have a hard time visualizing 506 tons of CO2, soOriel provides equivalents: planting 2,228 trees, offsetting theannual emissions of 113 cars, or, because they’re Australianand it’s humorous (and true), offsetting the annual emissionsof 219 cows.

Whatever your view on the IT benefits of virtualization orwhether you want to argue with the specifics of the assump-tions in these estimates, it’s tough to argue with the basicpremise: Virtualization yields fewer physical servers in yourdata center. No matter what virtualization host platform youchoose, fewer boxes equals less electricity consumed. Lesselectricity consumed equals fewer emissions.

VMware has taking green savings one step further. Distrib-uted Power Management (DPM) is a new feature of its Distrib-uted Resource Scheduler (DRS) module of ESX (and soon tobe part of vSphere.) Relying on VMotion and DRS, VMwareclusters can selectively shut down physical hosts as load re-quirements decrease, further consolidating running virtualmachines to a subset of hosts. As loads ratchet up again, of-fline hosts power back up via wake-on-LAN, and VMs redis-tribute as more capacity is required. VMware projects an ad-ditional 20% power and cooling savings thanks to DPM.

—Joe Hernick

GLOBAL WARMING SSAAVVEE MMOONNEEYY,, SSAAVVEE TTHHEE PPLLAANNEETT




>> Virtual Iron Extended Enterprise Edition 4.5 is just what is advertised: a full-featured enter-prise virtualization platform. Although it could easily play in larger enterprises, the companysees opportunity at the smaller end of the market, where VMware often prices itself out of con-sideration.

Virtual Iron’s pricing model is per socket, so a 16-core cluster would set us back $799 per eachof our eight sockets, a total of $6,392. Quad-core installations would yield better bang for thebuck—$3,196 if we happened to be running 16 cores across four four-way hosts.

VI-Center, Virtual Iron’s Java-based central management and network distribution tool, pro-vides a centralized install that had our cluster up and running in less than an hour.

Virtual Iron partners with PlateSpin for physical-to-virtual technology; pricing includes six con-versions per socket license.

>> Not to be outdone, VMware came to the Rolling Review loaded for bear—or bare metal, asit were. VMware has the largest ecosystem of vendors and support, and VMware InfrastructureEnterprise 3.5 is fully equipped, with resource management, power management, VMotion/Storage VMotion, high availability, Update Manager, and VirtualCenter for $6,958 per twoprocessors. Our 16-core cluster had eight processors, for a steep total of $55,664.

VMware’s pending vSphere repackaging may shake up the SMB competition later this spring.Then again, it may not: The entry level of vSphere, where the most dramatic savings play outat $795 per processor, lacks VMotion and other features. Again, this is a deal breaker. Steppingup to the just-announced vSphere Enterprise level will deliver VMotion to the SMB audience… for $2,875 per processor.

>> Parallels Server for Mac 3.0 trails the other products we tested in functionality, reporting,and day-to-day management. Nevertheless, Apple-only shops should give it a look because it’sthe only Mac OS X 10.5 Server support vetted by Apple. In our tests, Parallels did getWindows 2003, OS X, and Linux hosts running side by side on Apple hardware. And Mac-cen-tric organizations can get optimized Xserve hardware and finally dump those pesky legacyWindows hosts. But at $1,250 per physical host, we’d only recommend it on four- or eight-way Macs.

We’re keeping our fingers crossed that Server 4.0 is coming soon, bringing live-motion capabil-ity, snapshots, and robust centralized management. If we had built out four Xserves withParallels, we’d be looking at a cool $5,000, but we don’t know of any Mac shops looking to





spend that kind of money on virtualization software. After all, $5,000 will buy some nice com-modity hardware to run a small, free Citrix Xen cluster.

TAKE A TEST DRIVEVMware, Citrix, and Virtual Iron all have full-featured demos available to try before you buy. Iftime allows, it may be worth the effort to build test clusters for your two top hosting candi-dates.

Live migration is a critical element of VM cluster management; however, you’ll be able to save alot of money if your organization can tolerate brief production outages to shuffle a VM fromhost to host. Likewise, assess your appetite for high-availability capabilities; high availabilitycomes at an additional licensing premium.

Finally, a warning: The VM tools in this Rolling Review made it ludicrously easy to create a vir-tual server. Too easy. Ensure that your virtual environment maintains the same rigor andchange-control discipline as the physical side of your shop. Wanton creation of guests and fluc-tuating resource demands can lead to “VMotion sickness.” Don’t let your virtual world get awayfrom you.


Technology

Analytics Alerts - Virtualization Leaders Get Put to the Test