18 communications of the acm | march 2009 | vol. 52 | no. 3 news s c r e e n s h o t B y c h r i s t o P h e r g l i s s o n I t’S no SeCRet that virtualizatio n, a technology long associated with mainrame computers, has been transorming data centers due to its ability to consolidate hardware resources and reduce energy costs. But in addition to its impact on data centers, virtualiza- tion is emerging as a viable technolo- gy or smartphones and virtual private networks, as well as being used to re- conceive agile and cloud computing. Over the past decade there has been a great deal owork on improv- ing the perormance, enhancing the fexibility, and increasing the manage- ability ovirtualization technologies. Developments in the past ve years alone, or example, include the abil- ity to move a running virtual machine, along with its live operating system and applications, to a physical host without major downtime. The indus- try has also recently witnessed the ability ovirtualization to log the ac- tions oa virtual machine in real time, with the purpose obeing able to roll back an entire system to an arbitrarypoint and then roll it orward or de- bugging or auditing. These and other recent developments have positioned virtualization as a core technology in cloud computing and have acilitated the technology’s move to the desktop. “It’s clear that virtualization is here to stay,” says Steve Herrod, chietech- nology ocer at VMware. “In the u- ture, we’ll look back at the nonvirtual- ized compute models as we look back at the phonograph and bulky CRTs.” But Herrod also says that the industry is ar rom realizing the ull benets that virtualization can bring to desktops, laptops, and smartphones. “Virtual- ization is picking up steam rapidly or desktop users, but it has certainly not achieved ubiquity yet,” he says. “End users don’t want or need to know that virtualization is being used; they want access to their applications, and theywant the very rich media experiences that many modern applications oer.” Arguably, one othe most interest- ing and novel uses othe technologyis on mobile devices, where virtual- ization enables several new use-cas- es, such as isolating work and home smartphones on a single physical handset. Gartner predicts that more than 50% onew smartphones will have a virtualization layer by the year 2012. The need or virtualization on smartphones is strong, says Herrod, particularly as these devices become more powerul, as mobile applica- tions become more advanced, and as security becomes a bigger issue. “Just as in the early days oour x86 desktop virtualization eorts, we see many di- erent benets that will come with this virtualization,” says Herrod. As one example, Herrod cites the substantial testing procedures that every new handset must undergo prior to shipping. Virtualization, he says, will let handset manuactur- ers test once and deploy on dierent handsets. For the carriers, Herrod pre- dicts that virtualization will enable a new set oservices, such as allowingusers to deploy a virtual copy otheir mobile data to a newly purchased handset. And or businesses, he says that those who want a single handset or home and work will be able to use dierent virtual phones. “Their work phone could be restricted to very spe- cic applications and corporate data that is secure and completely isolated rom their home phone, where theymay have personal inormation and games,” he says. “The more we talk with people about this new area, the more use-cases we nd.” ed sry The notion that one othe strengths ovirtualization is its ability to isolate data and applications corresponds to another aspect othe technologyTechnology| DOI:10.1145/1467247.1467253 Kirk L. Kroeker tevlVrlzVirtualization is moving out of the data center and making inroads with mobile computing, security, and software delivery. ampr, wVmwrf, wblrWdwXP Prlr, WdwVhrg, d mos X Lprd bkgrd.
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8/14/2019 Technology | DOI:10.1145/1467247 .1467253 Kirk L. Kroeker
march 2009 | vol. 52 | no. 3 | communications of the acm 19
Quantum Computing
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that has become increasingly popu-
lar. While it might be easy to think
o virtualization as adding a sotware
layer that requires additional controlsto maintain security, proponents o
virtualization argue that it serves the
opposite purpose, and instead rep-resents a core enhancement to secu-
rity. “The only way we know how toget strong isolation is to keep thingssimple,” says Mendel Rosenblum,
ounder o VMware and a proessor o
computer science at Stanord Univer-sity. “And the only way we know how to
do that is to have isolation enorced at
the lowest level.”
Modern operating systems have ahigh level o unctionality—and a cor-
responding level o complexity and
number o potential weaknesses. “I
look at virtualization as a step towardgetting out o the mess we have in
terms o these systems being so in-secure,” says Rosenblum, who main-
tains that better security is a natural
result o virtualization. Still, he says, itis incumbent on those working on vir-
tualization to build layers that don’t
make virtualized systems so ull o ea-
tures and complex that they becomedifcult to secure.
Ian Pratt, ounder o XenSource and
vice president o advanced products at
Citrix, has a similar view o virtualiza-tion’s relationship to security. “I you
look at hypervisors or laptops andphones, it’s not about consolidation,”
he says. “It’s about security and being
able to secure dierent partitions on
a device.”Citrix is developing sotware or
a model o mobile computing that
the company calls “bring your owncomputer,” with the idea being or
employees to use their own laptop
or securely connecting to the corpo-
rate network. In this model, the lap-top runs a corporate virtual machine
directly on top o a hypervisor ratherthan in a hosted virtual environment
contained by the employee’s personal
operating system.
“You need to provide very strict iso-lation between those environments
because you really don’t trust the per-
sonal environment,” says Pratt. “It isonly through using a hypervisor where
you can achieve that strong isolation
between those environments.”Like VMware’s Herrod, Pratt points
to smartphones as one maniestation
o this new way o thinking about vir-
tualization and security. In Pratt’sexample, a handset might have one
virtual machine that controls the ra-
dio, another that contains all the de-ault sotware and applications, and athird that operates everything the user
downloads and installs. “The whole
idea behind this,” says Pratt, “is thatbecause you have this strong isolation,
no matter what rubbish you download
and install on the phone, you are stillgoing to be able to make that 911 call
whenever you need it.”
Proponents o virtualization say
that, in addition to acilitating new ways o enorcing security, virtual-
ization technologies are leading tonew ways o distributing sotware.“Virtualization not only gives you the
ability to manage hardware more e-
ectively,” says Rosenblum, “but alsoallows you to treat the sotware you’re
running dierently.” One way o lever-
aging virtualization’s capabilities isto ship complete packages o running
virtual machines rather than having
users assemble operating systems
and applications themselves, he says.The idea represents a dierent take
on sotware as a service, a model thatobviates the need or users to assem-ble applications themselves. “It’s not
like you buy all the separate parts to
make a car, but that’s what we do withcomputers,” says Rosenblum, who
must be isolated rom other applica-tions will be virtualized. The result?
“The main noticeable thing will be
more trustworthy computing,” says
Pratt. Echoing this sentiment, Herrodpredicts that users won’t think about
virtualization as a dierent orm o computing. “It will seamlessly ft into
our notion o computing,” he says,
“enabling a much simpler and moreproductive experience or all o us.”
Bed in lo angee, Kirk L. Kroeker i freeneeditor nd writer peiizing in iene nd tenoogy.steven hnd, citrix, nd cr Wdpurger, Vmwre,ited in te deveopent of ti rtie.
Obituaries
In Memoriam
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