Server Virtualization refers to a complete operating system that runs in a guest virtual machine (VM) on the host operating system. This host operating system is know as a “hypervisor” (such as VMware ESX, Microsoft Hyper-V Server 2008, and Citrix XenServer). This guest VM is completely independent of the host operating system and can be moved from one server to another or even run on another hypervisor platform entirely if converted. Since each guest VM is completely enscapsulated, you have the ability of running multiple VMs on one server. The hypervisor which sits between the physical hardware and the guest VMs manages the shared resource allocation of the server. This allows you to take advantage of the resources of a physical server that would otherwise sit idle. When you tally up the cost of electricity, air conditioning, space, battery backups, etc., you will find that if your environment has many servers, the costs can get very high very quickly. This is where server virtualization has it’s greatest benefit. Add to this the flexibility of moving your server to another server on the fly in the event of a hardware failure of disaster scenario, virtualization goes from being a “cool trend” to a “must have” for many companies these days.
ESX, Hyper-V Server 2008, and XenServer Enterprise are all “bare-metal hypervisors” which means they do not require an operating system installed on the server at the time of the hypervisor installation. They are in essence their own OS. You will notice however that ESX is based on Linux Redhat and Hyper-V is based on Server 2008 Core.
The other kind of hypervisor is the software hypervisor that requires a host OS already installed on the server or desktop to run. Examples would be VMware Server, XenServer Standard, Hyper-V (the one that ships with Server 2008, not the baremetal version above that you have to download online). The good thing about using a software hypervisor is that you don’t have to reformat an existing server to install a hypervisor. You can continue using the existing server as you always have with the added benefit of having one or more virtual servers running right along side it. The downside of using a software hypervisor package within a host OS is increased overhead.
This is just the tip of the iceberg. There are so many virtualization options available, which one is correct for small and medium size business? Most SMBs typically enter the virtualization market for two reasons:
1. High availability of a server (such as a mail server, web server, etc.)
2. Total cost of ownership & ROI (the company realizes that buying yet another physical server is not cost effective)
The next question an SMB should ask is how much is it going to cost to virtualize and consolidate your servers? Without going into too many details and comparisons of features, the typical small to mid size business can virtualize for free using a free hypervisor as long as your exisitng physical server will support it:
1. VMware Server – FREE
2. Hyper-V Server 2008 – FREE
While other hypervisor options include many different features, using VMware Server or Hyper-V Server 2008 are two ways an SMB can see what a hypervisor can do for them without the making a huge investment in buying Enterprise class software such as VMware ESX or XenServer Enterprise.
VMware Server should be considered the entry level hypervisor for SMBs. This is absolutely free and will install on your existing Windows 2003 Server just like any other application. The hardware requirements are flexible. The only thing you have to worry about is having enough RAM available for your guest machines. VMware Server cannot be used for high availability, you will have to purchase it’s bare-metal big brother ESX. Using VMware Server is a great way to see how powerful virtualization can be in your environment first hand. If you choose not to go the virtualization route for whatever reason, just uninstall it from your server just like any other application.
Hyper-V Server 2008 is a free download on Microsoft’s website. One important point to note for Hyper-V is that since it is a bare-metal hypervisor, you cannot install it on an existing server without first formatting it. The hardware requirements of Hyper-V also have to be met. The biggest problem SMBs usually face is that their existing server is not 64 bit and the processor does not support hardware assisted virtualization (Intel VT or ADM-V). Most SMBs will likely have to purchase a new server for this purpose since these hardware specs have only been in the market for just over a year now. So for an SMB that wants to get a taste of actual bare metal virtualization at the cost of purchasing a new server, Hyper-V is an excellent choice. The good news is that this is completely scalable. If you want to purchase additional servers and setup multiple Hyper-V servers, you can basically “daisy chain” them all together and create a high availability solution. If one physical server were to fail (let’s say a power supply goes out), it will Quick Migrate the servers to other physical servers as long as you have some kind of shared storage setup between all the servers. Your users will never know something has happened since the migration is seamless.
In summary, there are many configurations and flavors of virtualization available these days. The solution you need will depend on what requirements your business has and what the budget is. IronTech consulants are certified virtualization specialists that can help you choose what’s best for your company on a variety of offerings from Microsoft, VMware, and Citrix. We have virtualization demonstrations available in Houston and Dallas and can even give you a “loaner” server to virtualize some of your servers to show you how seamless yet powerful server virtualization can be.
