The majority of attendees at the Data Center Decisions conference in Chicago last week reported that they are either...
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deploying virtual machines or are interested in learning more about the process.
The first step in migrating from physical machines to virtual servers is developing a solid plan, said Chris Wolf, senior analyst at Midvale, Utah-based research firm Burton Group. Wolf hosted the conference session "Processes for choosing virtualization candidates in large-scale deployments."
"People who have done virtualization will tell you: Planning is 90% of the process. The other 10% is the actual migration, which is easy," Wolf said.
The blueprint for virtualization starts with an evaluation of virtualization platforms, namely VMware, Xen, SWsoft or Virtual Iron Software.
Then Wolf suggests estimating the number of virtualization candidates (servers with low utilization rates, for instance) and developing a business case for the technology. Wolf also counsels IT practitioners to estimate the impact on hardware and facilities and analyze the existing environment to determine virtual machine and physical host placements in their data centers.
"I certainly think virtualization is well worth any risks you are taking on," Wolf said. "The biggest risk is support from ISVs [independent software vendors]."
But that doesn't mean the risks are insignificant. And with virtualization, a central hurdle is ISV licensing policies. Vendors like Oracle lag in support and licensing policies for virtual technologies. One conference attendee who works in IT at a hospital, for example, said he hasn't started using virtualization because his ISVs won't support or license their applications to run on virtual machines.
Of course, users can migrate their apps to virtual machines on the sly and, if issues arise, migrate them back to physical machines and get their ISV support, Wolf said.
Once the virtual infrastructure plan is documented, selling the case to upper management can pose a problem, but the benefits of improved availability for all applications; infrastructure flexibility; lower long-term hardware costs; reduced power consumption; and easier testing, training and deployment should ease skepticism, Wolf said.
Sites like VMware's TCO calculator, which shows total cost of ownership over a three-year period, should help make the case. TCO for virtualization is viewed over a three-year period because the first year likely involves acquisition of new 2U servers or blade servers, networking equipment, and more storage area network (SAN), said Wolf.Decisions, decisions
When selecting a virtualization platform, consider your operating system and applications, ISV support, and performance in your everyday environment, Wolf said.
"Performance benchmarks are published, and those are great. But come on, we know vendors skew systems to make them as optimal as possible. The only way to truly test performance is to run it in your own environment and see how it works for you," Wolf said.
Virtualization platform vendors typically sell short 30-day licenses that allow you to test products in your own environment, which is strongly suggested for smaller, less mature platform providers, Wolf said.
Compared with OS virtualization, server virtualization is a better option for legacy server consolidation, dedicated application servers and domain controllers, Wolf said. Platforms include VMware ESX Server , XenServer and Microsoft Virtual Server R2.
It's also important to recognize that some virtualization platforms, like XenSource or VMware ESX, have a set list of hardware they support, so check for compatibility with hardware and applications, Wolf said.
"When choosing virtualization candidates, start small with systems that run the lowest workloads and allow you to use a cookie-cutter approach to migration until the IT staff gets comfortable with the process," Wolf said.
Nearly all of the 100 or so attendees at Wolf's session said VMware is their platform of choice, while only one attendee in the crowd said he is considering Xen. The same went for Microsoft.Migration tips
Collect your system information for migration and recovery purposes for at least a month -- and ideally six months -- prior to undertaking a migration, Wolf said.
Also at the Data Center Decisions conference, virtualization consultant and analyst Andrew Kutz gave tips on physical-to-virtual (P2V) migration and some common pitfalls to avoid.
P2V application migrations can be done manually or by hot migration, offline imaging, or bare-metal restore. When migrating P2V, hot clone and manual migrations are your best bet , Kutz said.
"Manual migration is the most hands-on type of migration, where you manually install OS applications in a VM, sync the data by restoring it from backup, do replication or manual copy," Kutz said.
Companies like LeoStream Corp., Platespin Ltd., VMware and a newer company called Invirtus Inc. offer online or hot migration tools. LeoStream's Leostream P>V Direct and Platespin's PowerConvert are more mature products than VMware Converter because P2V migration is their sole focus, Kutz said.
Platespin offers the only tool that fits into a heterogeneous data center and has the ability to convert both Red Hat Linux 7.3 and SUSE Linux Enterprise Server 9 and up in addition to Windows NT/2000/XP/2003.
Hot migration works about 95% of the time because of hardware failures. Source system drivers copied to a new VM, for instance, may cause a stop error when you attempt to load applications. PlateSpin's PowerConvert does a good job of removing physical device drivers on the fly to bypass this issue, Kutz said.
Users should also be aware of price variances. Those with a Virtual Infrastructure license from VMware get VMware Converter for free, but if you want a dedicated converter and don't mind paying for it, Kutz recommends PlateSpin or LeoStream.
Virtual Iron and XenSource, which was recently acquired by Citrix Systems Inc., are maturing in this space, and Kutz expects to see some interesting technologies emerge over the next year.
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