In some way, virtualization is a VMware world. Everyone from SAN to server to network vendors has some kind of tie in to VMware. VMware runs on over one-third of Cisco's Unified Computing System units that have been deployed to date. Enterprise management platforms such as HP Insight are being extended to include deep support for VMware that simplifies and expedites the management of hordes of virtual machines. This is important because it keeps operations flowing smoothly and allows you to use a similar process to manage virtual servers as you did when managing physical servers. Everyone knows that process already and it will decrease the burden of migration and help achieve a faster ROI.
Far and away the most popular hypervisors are those made by VMware. The primary draw is the ubiquity of VMware. With the vCloud initiative you could build your own dynamic data center running VMware's vSphere and vCenter and then automatically scale up and down using external Cloud providers. There are over 1,000 Cloud service providers that are "VMware Virtualized" plus countless others that have adopted VMware's vCloud API.
Sarrel's Short List
Server virtualization revolves around the hypervisor, the software that sits on top of the hardware (either directly as "bare-metal" or on top of an OS), partitions the hardware into multiple virtual machines, and manages interactions between hardware and virtual machines. There are currently three main choices for a server hypervisor: Microsoft Hyper-V, VMware (ESX and vSphere), and Xen (an open source hypervisor supported by Citrix).
Heres the skinny on choosing a hypervisor:
1. VMware should be at the top of everyones list because theyve been doing virtualization for more than 10 years. No one doubts VMwares ability to deliver a reliable hypervisor and extensible management tools. Developing a hypervisor with excellent performance, reliability, scalability, and manageability doesnt happen overnight, and these are critical features for an enterprise computing environment.
2. Microsoft is a relatively new comer with Hyper-V and based on the success of SharePoint, I believe that anything Microsoft gives away with their server software has an excellent chance of being implemented. Like most Microsoft products, Hyper-V isnt the best and will probably never be the best, but it is bundled and pre-installed so why not enable it and give it a shot?Related Articles
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3. Xen is an excellent choice for budget conscious shops that have implemented Linux servers. There is always a trade-off between cost and power/utility. During these times of economic hardship, companies are more willing than ever to make that trade. Also, if you rely heavily on Citrix for your server infrastructure, then their support for Xen should be an important purchasing consideration.
4. If your goal is to have dozens or hundreds of virtualized servers residing in multiple physical locations and forming both internal private and external public clouds, then your only real choice right now is VMware vSphere due to its scalability and manageability. VMware currently owns the high end enterprise virtualization market.
The Nitty Gritty
Microsoft Hyper-V - Microsoft provides a limited version Hyper-V free of charge plus there are various flavors that come with the various forms of Windows Server 2008. Hyper-V starts with support for up to 8 CPUs and 1 TB RAM in the host machine and goes up from there. Microsoft focuses on using virtual machines to increase application and server availability, therefore an important feature is live migration, or the ability to move running virtual machines from one Hyper-V physical host to another without disruption of service. If you are a Microsoft shop, then it may make some sense to get your virtualization feet wet with Hyper-V because you've already got it.
VMware ESX - This is the most widely implemented hypervisor today (most virtualization professionals cut their teeth on some version of ESX). The current version supports up to 64 logical processing cores, 256 virtual CPUs and up to 1 TB RAM per host and will run a broad range of guest operating systems including Windows, Linux, Solaris, and NetWare. Virtual machines can boot from local or shared SAN storage. VMware vStorage Virtual Machine File System (VMFS) is a clustered file system that allows multiple ESX hosts to access a single virtual volume concurrently, paving the way for shared storage via Fibre Channel SAN, iSCSI SAN, or NAS.
VMware vSphere 4 - More than a hypervisor, vSphere 4 is a data center Cloud computing platform built on VMware ESX. There was a lot of buzz earlier this year when vSphere shipped because it promises to control internal and external virtualized Cloud environments by automating management and dynamically allocating resources to migrate live virtual machines across physical machines to minimize service interruption. For example, an application could automatically scale up and down using both internal and external virtual Cloud resources. An important consideration is there are huge numbers of API's and third party add-ons, so industry support is strong and getting stronger for vSphere. sources.
Xen - The Xen hypervisor is an open source alternative which provides efficient and secure virtualization of x86, x86_64, IA64, ARM, and other CPU architectures. It supports a wide range of guest operating systems including Windows, Linux, Solaris, and various versions of the BSD operating systems. It was developed in conjunction with engineers at over 50 data center solution vendors, including AMD, Cisco, Dell, Fujistu, HP, IBM, Intel, Mellanox, Network Appliance, Novell, Red Hat, Samsung, SGI, Sun, Unisys, Veritas, Voltaire, and Citrix.
Xen has a reputation for being lean and mean; high performance and not many management features like others mentioned in this article. You can add the Xen Cloud Platform to gain sophisticated management features similar to those found in VMware vSphere and Microsoft System Center Virtual Machine Manager.
Keys to a Successful Implementation
Develop a clear business case in favor of virtualization that demonstrates an ROI and a reduced TCO. Start by assessing your current physical server environment. Where previously you scaled up by adding more physical servers, reduce costs by consolidating them into multiple virtual servers running on a single physical server. This not only reduces the resources needed today, but you can reap future rewards of more efficient scaling using a virtual platform. There's also the potential of decreasing the cost of your business continuity program because, unlike physical machines, virtual machines can be pushed from one location to another.
Beware of potential licensing and support implications, however. It's possible that a particular application's licensing policy changes when run on a virtual server so look before you leap. Also, verify that the application is supported on your virtual platform and that tech support has the know-how to help if needed.
Allocate time and resources towards planning this wide-sweeping change in your enterprise architecture. Virtual servers are different from physical servers so policies, procedures, and concepts will have to adapt. It should go without saying to make sure there are backups and archives of physical systems. Try to get a handle on how much hardware is required for each virtual server and then make sure you allocate properly. Especially keep an eye out for "virtual sprawl", or the sometimes magical ability of virtual environments to expand out of control until they are unmanageable. Finally, understand how the timing of this project affects other IT initiatives and make sure that all other projects include virtualization support.
Make migration as smooth as possible for end users. The best outcome would be if no one even noticed that you've gone virtual. In order to do this, monitor performance and availability of pilot and initial deployments. Upgrade hardware as needed to meet performance and availability goals.
Benefits of Virtualization
Virtualization can reduce costs related to underutilized physical servers. Many enterprises purchase servers with the plan that use will grow to fit the resources―if our application uses five percent (5%) of resources today then we'll be good for a few years as it grows to 50%. But this means that you're paying for tomorrow's resources today and we know technology resources get cheaper over time so this excess capacity is basically wasted. Running a number of virtual machines on a single physical machine allows IT departments to use that extra capacity.
Running multiple virtual machines on a single physical machine also consolidates the physical server footprint in the data center. And fewer physical servers means less rack space, energy consumed and heat produced, plus the accompanying reduction in administration costs.
Virtualization provides a great deal of flexibility by divorcing the OS and applications from the server hardware. You can add or remove resources from the virtual machine without shutting down the physical server and disassembling it. Remember the agony of the last time an application was jeopardized by failing hardware? In a virtualized environment the application's virtual machine could simply be pushed to different hardware. This flexibility facilitates more efficient scaling of server environments as business needs grow.
Matt Sarrel is executive director of Sarrel Group, a technology product test lab, editorial services, and consulting practice specializing in gathering and leveraging competitive intelligence. He has over 20 years of experience in IT and focuses on high-speed, large scale networking, information security, and enterprise storage. E-mail: firstname.lastname@example.org. Twitter: @msarrel.