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Free VMware versus pricey VMware ESX Server, part two

In part two of this series, Alessandro Perilli further explains the differences between VMware Server and ESX Server by comparing the security and support of each.

VMware Server and ESX Server are both great choices, but how do you know which one is right for your enterprise? The two have distinct differences, and only after careful consideration can you determine the best choice for your circumstances.

In the first part of this series, we examined the key differences between the free Server (once known as GSX Server) and the expensive ESX Server. We learned that the primary difference between the two is that Server is a so-called hosted solution (that behaves like a typical application) and ESX Server is a bare-metal solution (that behaves more like an operating system).

This distinction affects performance and flexibility, both of which are obviously important considerations for in mission critical solutions. But the underlying technological approach is not the only area in which VMware Server and ESX Server differ.

In this article, we'll go over a few more key points that you need to consider before you can decide which product best fits your needs.


ESX Server has all the characteristics of the solutions commonly known as appliances.

A typical appliance is a black box with its own operating system, tailored for performances and minimal attack surface, with a preconfigured application on top (a firewall, an antispam application, etc.). Inside, customers find essential (and sometimes insufficient) tools for administration. The vendor usually doesn't support any software that could introduce vulnerabilities in the system.

ESX Server's appliance approach is a double-edged weapon. On one hand, it simplifies the complex task of securing the corporate environment and keeps administrators from having to fret about system patching. When a new vulnerability appears, the customer just has to wait for VMware to release the proper patch or a platform replacement.

For these reasons, appliances (and ESX Server) have a lower total cost of ownership (TCO).

But on the other hand, customers have little or no ability to perform any emergency operations on vulnerable platform components. If a system is exposed to attacks, but VMware is slow to release a patch, administrators have to mitigate the risks or avoiding using the compromised feature.

In some highly secure environments, a black box is not allowed at all by corporate policy because of the inability to fully control the platform.

In a hosted solution like VMware Server, we have the opposite problem. Full control on the operating system behind the application means you need a lot of knowledge to figure out how to secure it. You also need time a tremendous amount of time to find, test and implement new patches. Most importantly, you need time to test the patch and assure its reliability before you apply it to production environment.

Patches may fix security vulnerabilities but then affect overall system reliability. A company should have a lab environment wherein production systems are replicated, a valuable network traffic generator and a team handling the whole QA phase.

It's evident this approach, which would be associated with VMware Server, has huge costs that few companies can sustain. The majority of customers have only two choices: 1) use a hosted solution but don't patch the OS until the application vendor (VMware, in this case) officially approves the patch or 2) turn to a black box solution.

Less savvy customers allocate time and staff for patch management but implement OS patches without testing them. This can work for less critical servers, but it can be risky on a virtualization environment, wherein reliability is crucil.

Learning curve

ESX Server has more features, which means it takes more time to be mastered and requires more employee training. For example, a company primarily running on Microsoft technology may encounter more problems with ESX Server, because ESX Server requires some limited knowledge of the Linux environment and commands.

Any delay in understanding the platform has consequences, because administrators have to learn how to interact with product and are slower in doing troubleshooting or performance tuning when they're not yet up to sped on the product's intricacies. This delay is bigger when a company decides to not invest in quality training.

VMware Server, being a hosted solution, can be installed on both Windows and Linux, which allows companies to best make use of existing employee knowhow.

Boosting products with VirtualCenter

Differences between Server and ESX Server can be considered limited. But this changes when they are used in conjunction with VirtualCenter.

Both Server and ESX Sever carry common enterprise management features like multi-host centralized monitoring console and virtual machine inventory, a template based repository for fast provisioning of new virtual machines, a granular permission system to control user access to virtual machines and a flexible alerting service.

But ESX Server is much more integrated with VirtualCenter than Server, and ESX Server can perform more complex operations like the famous VMotion (migration of a virtual machine from a physical host to another without interruption of service).

This integration is even tighter with the new ESX Server 3.0 and VirtualCenter 2.0, together making up VMware Infrastructure 3, which permits even more acrobatics. The new platform is able to perform feats such as detecting failures on a physical host and restarting a lost virtual machine on a different host in the data center.

Another impressive VI3 capability is that it can dynamically move an overloaded virtual machine from the physical host where it's running onto a less busy server -- all without manual intervention and without interruption of service.

Although these features drastically lower maintenance costs, they carry a huge investment in terms of hardware equipment. Without a fast network connection and an expensive SAN infrastructure, you cannot realize the benefits of these features.

At the time of this writing, VMware Server cannot provide these advanced features, since only VirtualCenter 1.4 can remotely manage the 1.x branch, and VirtualCenter 1.4 is limited.

Future releases of VMware Server are expected to be managed by VirtualCenter 2.0, but it's unclear if these advanced capabilities will be unlocked for the free platform. Until that time, whoever decides to adopt Server will have to rely on third-party solutions (like the one provided by vizioncore) to obtain capabilities similar to those of VMware Infrastructure 3.

Even VirtualCenter 1.4, despite its limitations, is not free; customers adopting the free Server but wanting centralized capabilities have to consider the overall price.

Vital support

As already mentioned in the first part of this article, free software can often be perceived as not fully functional, reliable or performing. Companies may avoid free software for these reasons. Some corporations may even disallow free software by company policy, because IT managers are scared by the idea they are relying on a product that has no economical model behind it and that the company producing it could suddenly stop supporting it.

To address this legitimate concern, VMware offers Server as a free product but also offers enterprise-grade commercial support for it.

Some smaller companies, when considering the differences between Server and ESX Server, do not consider support to be a mandatory need. They instead plan to rely on online documentation, support forums, blogs and books to solve any issues that arise during the virtual infrastructure lifecycle.

Unfortunately, a large number of factors make things more complex than that, including incompatibilities with some hardware configuration, unexpected behavior of some virtual machines (depending on hosted applications), sudden performance bottlenecks at host level and other issues.

Any virtualization platforms should be considered a mission-critical tier. So many virtual machines and related services may rely on the platform, leaving customers with few reasons to avoid purchasing commercial support.

In this respect, Server and ESX Server are identical, with both offering Gold and Platinum support plans.


VMware Server and ESX Server offer different approaches to solve the same problem, and they address different company needs.

Customers looking for maximum performance and partial data center automation should look at ESX Server, knowing it carries a significant cost in hardware equipment, implementation efforts and training time.

Customers looking for a faster startup time and a more flexible solution can adopt VMware Server with confidence. It's reliable enough for any virtualization project.

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