Author and programmer Eric Hammersley had launched into using VMware Server when he realized virtualization’s space and cost-saving potential. At the time, he was installing multiple server and switch racks on a ship for the U.S. Navy. His book Professional VMware Server: Programmer to Programmer discusses installing and configuring VMware Server, tips for creating base imagines, image library organization best practices, integrating and leveraging VMware for your environment and more.
In this interview, Hammersley shares his thoughts on Microsoft Hyper-V and VMware ESX, explains basic virtualization architectures, and compares the three major VMware offerings: VMware Server, VMware ESX and VMware Workstation.
SearchServerVirtualization.com: Your book Professional VMware, Programmer to Programmer makes it’s clear that you’re a fan of VMware. Do you think Microsoft Hyper-V will affect VMware adoption?
Eric Hammersley: No, not yet. Virtualization is a disruptive technology (to use a rather brainy marketing term), and VMware leads the movement, though Microsoft has two advantages in this battle. First is the observation of trends in the technology. They have the benefit of VMware having been in the virtualization market for many years. No doubt, Microsoft has been following how VMware’s technological advances and has been analyzing this information for years. If you dig deep into Hyper-V you’ll see that its virtualization layer and approach is different than that of VMware’s. Did Microsoft discover a better way? Only time will tell.
The second advantage Microsoft has is sheer market dominance in the products that a very large percentage of VMware customers want to virtualize. If you’ve ever tried to virtualize an Exchange Server, you’ll know what a treat it is. As a virtual server, if Exchange has any kind of load it doesn’t work well enough for production use. Microsoft has a clear and rather major advantage in that regard. It can develop its server platforms and enterprise applications to utilize Hyper-V in a way that no one else can.
Do I want Hyper-V to succeed? Yes, mainly because I’m out here on the front lines virtualizing domain controllers, Exchange Servers (or trying to), SQL and many other Microsoft products. Hyper-V done right will make my job easier; done wrong and I’ll be spending time explaining to people with checkbooks why their virtualization initiative didn’t work well.
We could also see some interesting developments with Citrix’s acquisition of Xen. We should all keep an eye on them. In the end, we all benefit from a diverse and rich selection of products.
You’ve mentioned previously that you didn’t work with VMware ESX because you prefer hosted architecture. Can you explain hosted or operating system virtualization versus the hypervisor or bare-metal approach?
Hammersley: Hosted architecture can be seen in products such as VMware Workstation, Server, and Microsoft Virtual PC, to name a few. A hosted architecture relies on an underlying operating system to provide driver support for the machine’s hardware. This reduces the virtualization software’s job in a sense because it doesn’t need to know how to talk with X or Y piece of hardware, just how to interact with the hardware via the host operating system –whether it’s Windows, Linux, or something else.
A hypervisor is a different beast, more of a bare-metal approach, if you will. You can see a hypervisor approach in VMware ESX Server. While with a hosted architecture you rely on the host operating system to provide driver and hardware support, hypervisor architecture performs this on its own. The drawback of this is obviously hardware support. A typical hypervisor package would provide its own kernel and drivers for select pieces of supported hardware, removing the need for a host operating system to provide the driver support. This offers a big advantage of increased resources for your virtual machines, but it comes at an increased cost.
Has the release of ESX 3.5 prompted you to reconsider VMware’s ESX product suite?
Hammersley: My problems with ESX in the past have always been with the limited amount of approved hardware, along with the high cost. As an IT professional who has spent a large portion of his career in smaller business, the price has always kept me away. On the bright side, at least VMware doesn’t charge per core.
A few weeks ago, I was brought onboard for a new project that will implement ESX Server to thousands of users in many key data centers across the country. The specifics are not important, but my love for VMware has grown even more. ESX Server is a great product — VMware Server on steroids, if you will. It’s sound, stable, and flexible. The scalability, plug-in modules such as VMotion, High Availability and others make it a perfect addition to the bigger business data center looking to modernize, streamline its processes, save some rack space, and cash, once you recoup the initial cost. I’m looking forward to really digging into ESX and plan on sharing my experiences with it, especially with the API.
What are the differences between VMware ESX, VMware Server and VMware Workstation?
Hammersley: Well, they all three squeeze out the virtualized goodness, but in slightly different ways. Right off, ESX Server is what’s called a bare-metal solution. While most applications today run atop the operating system, be it Windows, Linux, or something else, ESX Server is everything rolled into one. ESX provides the operating system and virtualization technology right out of the box. Since ESX provides the operating system it offers a very tight and robust virtualization layer between the hardware and the provided operating system.
In addition the ESX operating system has a very small footprint, only about 32 MB, which allows greater amounts of system resources for your virtual infrastructure to utilize. It is, however, pretty pricey; so ESX is more of the Cadillac, if you will, of the product line.
Next would be VMware Server, which is what my title is based on. VMware Server is really a child born from a previous product called GSX Server. Both ESX and GSX provided ultimately the same thing: server-based virtual machines served out via client applications installed on the desktop. GSX’s reduced price and greater flexibility in terms of hardware made it a populate substitute for ESX.
Now, in 2006, VMware announced the demise of GSX Server in favor of its new, and free I might add, VMware Server product. Why they made the shift away from GSX in favor of a new free product is a question for them, however, the move caused an extraordinary amount of excitement. With the new VMware Server we’d get the same server based virtual machines, still served out via the VMware client application to the desktop, still with the APIs and automation capability, but with a reduced price tag. What more could you want?
Finally there’s VMware Workstation. The workstation flavor is just that: a workstation-only virtualization product. For many years it lacked APIs required for automation, the ability to run virtual machines as services in the background, and the ability to perform centralized management. This made it rather crippled in terms of functionality. Many of the features I mentioned above, however, have made it into the newest VMware Workstation, including API automations, a long-awaited feature. Honestly, I spend more of my time on VMware Workstation than any other product due to its snapshot support and ease of use. This doesn’t mean it’s a better product than VMware Server, it just fits my needs a little better.
Do you prefer VMware on Linux or VMware on Windows?
Hammersley: It depends. I prefer VMware Server on Linux when I really need to squeeze out every piece of performance I can get. Linux, on average, has a greater amount of system resources available because the operating system footprint is considerably smaller than Windows. The catch however is that the configuration and management can be a bit of a trick sometimes, and if you have a mostly Windows shop you’ll have trouble getting staff buy-in.
VMware Server on Windows offers a simple install and configuration. The management of VMware Server on Windows is also pretty easy. The downfall, and this can be huge, is system resources. Your memory and CPU available to virtual machines is drastically lower on Windows than Linux. This means fewer virtual machines can run on a Windows install if you compare it to Linux with similar hardware.
In the end, it’s really about what fits into your environment.