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VMware Server to ESX 3.5: Four steps for a successful migration

Planning on migrating from VMware Server to VMware ESX 3.5? Make sure your upgrade is successful with these four steps: evaluate your current environment, design your virtual infrastructure, test your migrations, and perform the migrations.

Planning on migrating from VMware Server to VMware ESX 3.5? Make sure your upgrade is successful with these four steps: evaluate your current environment, design your virtual infrastructure, test your migrations, and perform the migrations.

David Davis

Moving from VMware Server to VMware ESX 3.x or 3.5 is an evolutionary step as companies move virtualization into production settings. In this tip, I give a step-by-step tutorial on how to plan and implement this migration successfully.

This is part two of my tip series on moving VMware Server to VMware ESX Server 3.x and/or 3.5 The pros and cons of upgrading from VMware Server to ESX 3.5 of going through this important migration are explained in the previous installment. Here, I explain the best ways to do it.

Step one: Evaluate you current VMware Server environment

Prior to making the move to VMware ESX Server, you need to understand your current environment. Perhaps your environment is small and you feel that you already know what you have. Still, this evaluation process is important. Here are some questions you should find the answers to before you perform any migrations:


  • How many VMware Server host systems do you have?
  • How many VMware guest systems do you have?
  • What is the configuration for each of those guest systems?
    • CPU utilization and number of virtual processors
    • RAM utilization and total amount allocated
    • Virtual hard drive – size, type (IDE or SCSI) and fixed or dynamic
    • What is the purpose of each virtual guest system? What are their priorities to the company?

While much of this analysis can be done manually, if you have a large number of servers, you might consider a third-party product like PlateSpin's PowerRecon.

Step two: Designing a ESX Server/VMware Infrastructure data center

Once you know what you have, consider what your new ESX Server VMware Infrastructure will look like. To do this, ask yourself the following questions:

  • How many VMware ESX Servers will you have?


  • What level of license will you obtain (as it relates to the features offered by that level of VMware Infrastructure)?


  • What type of Storage Area Network (SAN) will you use? Fibre Channel? iSCSI?


  • What level of fault tolerance is needed for the ESX Server host systems and the storage area network?


  • How will you backup these virtual machines and how will you monitor performance? (Is third party backup software or third party performance monitoring software needed?)


  • Based on the current virtual hardware configuration of your VMware Server guest systems and the utilization of that hardware, how will you layout these new VMware ESX Server guest systems across the new VMware ESX Servers?


  • Is your ESX Server administrative staff up to date on their ESX Server training? If not, you should consider a training program for them. VMware ESX Server is a much more complex application than VMware Server.

At this point, I would be clicking on the Microsoft Visio icon and diagramming out the new VMware ESX Server infrastructure, detailing what server will go where.

Step three: Test migrations of VMware Server systems to VMware ESX Server

While you do need the overall grand plan to migrate all VMware Server systems to VMware ESX Server, when you finally initiate the process, you won't do all servers at the same time. There is simply no need to take that big of a risk and make such a large change all at once.

Because you have the luxury of being able to migrate one machine at a time, you have the luxury of being able to test each machine for some time before making the real migration. Both to test the migration and to perform a real migration, you will certainly need some tools. These tools could be built in VMware ESX Server tools or third party tools. Here are some tools to help in the migration from VMware Server to ESX Server:

  • VMware's vmkfstools – This command line tool can be used to import virtual guest machines that came from VMware Server or VMware Workstation. These imported guest machines must have fixed SCSI disks and you must have transferred them to the ESX Server with a utility like Fast SCP. For more information on how to import virtual machines with this method please see this thread at the VMware community forum.


  • VMware Converter – The Starter Edition of VMware Converter is free and you can download it from VMware's Web site. There is an Enterprise edition that is included with VMware ESX Server. For more information on how to import virtual machines with this method please see this thread at the VMware community forum.


  • Vizioncore's vConverter – This is a third party tool for conversions that claims to be the fastest converter on the market. If you are evaluating third party tools, I suggest you take a look at vConverter.


  • PlateSpin's PowerConvert – If you have hundreds or thousands of servers to convert and are willing to spend some dollars on a tool to assist you in this conversion, you should consider PlateSpin's PowerConvert. This is a powerful P2V and V2V converter.

Testing the migration of your production virtual systems is a critical piece of this process. You don't want the new & costly VMware ESX Server implementation to look like a bad investment for your company due to a conversion that was a flop.

Step four: Perform the migration to ESX Server

Finally, once you have done your analysis, design and testing, you are ready to perform your VMware Server to ESX Server migration. Again, this doesn't have to be done all at once, you can migrate one machine per day or per week, or whatever fits your company and your resources best. To do the conversion, you will likely use one of the tools mentioned above. Some of these tools may even provide you "hot conversions" so that there is no downtime or just seconds of downtime for the machines that are being converted.

And keep in mind that once the conversion is done, you won't be able to just sit back and relax. VMware ESX will certainly require a lot of monitoring and tweaking along the way. Just like any larger enterprise application, ESX Server and the VMware Infrastructure software suite will always require a competent administrator monitoring the virtual datacenter.

Pay attention to the basics

In this article, we detailed the steps you should take to move your VMware Server guest virtual machines to VMware ESX Server. The basic process is evaluate, design, test, and implement. Make sure you have fully answered all the questions we covered in each section before moving forward.

VMware ESX Server is absolutely a better solution than VMware Server for enterprise data centers, but you must make sure that you migrate to ESX Server properly to ensure that the project is a success!

David Davis has served as an IT Manager for over 15 years. He has a number of certifications including CCIE #9369, MCSE, CISSP, and VCP. Additionally, David has authored over one hundred articles, a number of video training courses, some of which are available at his Web site,

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