The top 10 cons of VMware virtualization: Challenging VMware critics

VMware may be the market leader, but skeptics remain hesitant to purchase VMware virtualization. Here are 10 cons lodged against VMware and an expert's rebuttals.

David Davis, Contributor
If your coworkers, boss or others argue that VMware virtualization has too many cons to make it worth the price and learning curve, you're not alone. Like you, I have heard various arguments against using VMware: My application development manager tells me, for example, that VMware makes Web servers sluggish. Third-party vendor representatives say that their applications are incompatible with VMware and that they won't support an application virtualized on VMware. Some magazine articles allege that Microsoft's Hyper-V offers better performance than VMware.

After using VMware, Citrix Systems' XenServer, and Microsoft's Hyper-V myself, I decided to create a list on the plusses of VMware, and you can use this list to counter the arguments lodged against using VMware. And if you are already sold on VMware virtualization, this article may make the case to your coworkers, boss or friends who are still in the process of choosing a virtualization platform.

As a matter of full disclosure, I am a VMware administrator and a vExpert. But I don't work for VMware, and this article is not sponsored by VMware.

1. Cost: "VMware is overpriced."
Before you say that I am wrong, note that I didn't say that VMware is the least expensive virtualization option. It isn't. That said, I believe that VMware's offering is worth the money. VMware's virtualization solutions are the most full-featured. No other virtualization technology has so many options (VMware High Availability [HA], VMotion, Storage VMotion, Update Manager, Distributed Resource Scheduler, Distributed Power Manager and memory overcommit). Also, no other virtualization option will have so many features in the near future.

So why would you pay five clams for a virtualization solution with five features if you could pay 10 clams for a technology with 25 features? You might want to pay the five clams for five features if you believe you can't afford to pay 10 or if you think you don't need the additional features.

But in the case of virtualization, eventually you will want those features. Your virtual infrastructure will grow quickly, and unexpected infrastructure needs will emerge. You will want a virtualization option that has more features than you need rather than one that has only the bare minimum.

If your budget is too tight to afford VMware, I encourage you not to settle for a less-featured virtualization solution. Trust me, I have worked with IT organizations that skimped on hardware or software and bought the least expensive product at the time and, in the end, it had to be thrown out and replaced. I encourage you to start with the best solution from day one and to ensure that successors aren't left with the problem of replacing a low-cost virtualization technology with VMware's enterprise-grade one down the road.

Instead of saying that you cannot afford it, use creative ways to justify purchasing the VMware solution that you want. Here are some creative justifications for purchasing VMware:

  • Cut spending in another area of IT spending to pay for VMware: Over time, you will get a return on investment. With VMware, you'll be able to make hardware and data center infrastructure cuts because of server consolidation.

  • Finance VMware software and pay for it out of your IT budget over time.

  • Buy the lowest level of the VMware Infrastructure suite and upgrade later.

  • Buy fewer licenses and add more later. You get many more virtual machine guest OSes on a single server than you think.

Now that we have gotten the cost argument out of the way, we can more on to easier issues to deal with.

2. Availability, reliability: "Too many eggs in one basket."
Certainly, with server consolidation via virtualization, you will have more servers on fewer pieces of hardware. Thus, you do have more eggs in one basket. To mitigate the availability and reliability issues created by this consolidation, you need to use features such as the following:

  • VMware High Availability (HA) – VMware High Availability will restart any guest OSes that run on a failed VMware ESX host. Thus, recovering servers after a host failure is quick and automatic.

  • VMotion – Use VMotion to move running guest OSes off ESX hosts when these hosts need to go down for maintenance or upgrades.

  • Storage VMotion – Use Storage VMotion to move virtual disks from an ESX host to a storage area network (SAN) or, if the host or SAN needs to go down for maintenance or upgrades, from one SAN to another.

  • Update Manager – Automatically update ESX servers or operating systems and applications on virtual machine guests with as little downtime as possible.

  • Fault Tolerance (FT) – In 2009, VMware will release its latest high-availability product, VMware Fault Tolerance (FT). You can use FT with HA or on its own. With FT, if an ESX host goes down, VM guest OSes need not be rebooted.

  • Site Recovery Manager (SRM) – VMware's Site Recovery Manager allows you to automate and test a disaster recovery plan.

By using features such as these, you can alleviate concerns about availability and reliability.

3. Reduced application performance
Certainly you need to take the time to understand any applications you virtualize to ensure that, once virtualized, they can achieve the same or better performance as that they achieved on physical servers. Still, if a virtual infrastructure is designed correctly, virtualization does not reduce application performance.

In my experience, physical servers can often be moved to virtual servers without end users noticing a difference. Prior to virtualizing, use something like VMware Guided Consolidation to select the ESX host and size for the proposed guest OS. VMware's Guided Consolidation can analyze physical servers over time to ensure that newly virtualized guests (and their applications) perform well.

4. Hyper-V and XenServer are better alternatives
While this article doesn't allow the space to compare VMware to its alternatives, let me just note that VMware has the most features, with many new products due out in 2009. VMware's virtualization technology has the greatest market share worldwide, and VMware's offering has the most grassroots support (meaning it features more how-to resources on the Internet and books, a larger community and more training options, for example).

All these pluses of VMware remain undisputed by its competition. Why choose a virtualization technology that doesn't offer continual innovation, myriad features and the support to handle them?

5. Hardware compatibility
Over the past few years, VMware ESX and ESXi have offered greater hardware compatibility. I encourage you to search the VMware Hardware Compatibility List (HCL) to check for your hardware. Even if your servers don't appear on the HCL, check whether they appear on the VMware whitebox HCL. Finally, I recommend that you just try it and see whether it works.

6. Application compatibility
In my opinion, the notion that some applications aren't compatible with virtualization is based on a misunderstanding of how virtualization works. Your applications don't need to be compatible with server virtualization; they won't even know that they have been virtualized (this is not the case for application virtualization, however).

I have seen Windows domain controllers, Internet Information Services, file servers, print servers, Citrix servers, Exchange servers and many more running on VMware ESX guest OSes. In fact, Microsoft has announced that its major enterprise applications support VMware ESX virtualization (see New Microsoft Virtualization Policies).

Again, if you are concerned that your applications aren't compatible, try virtualizing the physical server and running the application in a guest OS. I am confident that you won't have any issues.

7. Learning curve
Some admins worry about the learning curve associated with virtualization. Sure, there is a learning curve but I assure you, the small-time investment pays off quickly by reducing the time spent administering servers, bringing up new servers, and trying to maintain a disaster recovery plan, for example.

As I mentioned previously, VMware's virtualization offering has the greatest grassroots support and, because of that, you will find the greatest number of books, Internet how-to articles, blogs, instructor led training courses, and video training courses (like my VMware ESX training course).

In fact, the learning curve for VMware's virtualization solutions is short. Many small and medium-sized business administrators have found that they can virtualize their infrastructure quickly and easily once they gain confidence with VMware's solutions

8. Waiting for the next version
Over the years, I have found that if you simply wait around for the next version to be released, you lose out for not adopting earlier. For more than a decade, VMware has made virtualization technologies. Virtualization is neither new nor cutting edge. For most companies, getting started with virtualization, the current version of VMware ESX and the VMware infrastructure may have more features than they could ever use.

Yes, a new version of ESX and VMware Infrastructure are due out this year, but instead of waiting, just buy software maintenance.

9. Microsoft will make VMware obsolete
Yes, some articles exist such as Citrix, Micosoft aim to corner virtualization market. I am sure that both Microsoft and Citrix will continue to put pressure on VMware. But given that VMware has been around for 10 years, these competitors will push VMware to innovate and make virtualization more affordable to all, but I believe that neither XenServer nor Hyper-V can make VMware's virtualization solutions obsolete.

10. Virtualization isn't secure
Security administrators and auditors have long voiced security concerns about virtualization. While just like other OSes VMware ESX Server may have security holes, it is far more secure than, say, Windows Server. And, if you choose to use ESXi, it has a much smaller vulnerability footprint and many fewer security holes, as it doesn't have a service console.

In 2009, VMware will offer two new security products: VMsafe and vShield Zones. VMsafe is a security framework with an API for third-party vendors to develop security products that work to secure your VMware Infrastructure. VShield Zones allows VMware administrators to create secure zones between groups of virtual machines. This way, security policies can be created for the virtual infrastructure and vShield Zones can enforce and audit those security policies.

Until these security options are released, try the free vWire ConfigCheck, which checks VMware ESX servers to ensure that they meet the VMware ESX security best practices.

David Davis is the director of infrastructure at TrainSignal.com. He has a number of certifications including CCIE #9369, MCSE, CISSP, and VCP. Davis has also authored hundreds of articles and six different video training courses at Train Signal, his most popular being VMware ESX Server. His personal website is VMwareVideos.com. You can follow Davis on Twitter or connect with Davis on LinkedIn.


This was first published in April 2009

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