Consolidating Servers Under Linux
Pages: 1, 2
Consolidating services under Linux: Part two
Another way to consolidate servers if you can't run all of your applications under Linux (if you're tied to Windows for Workgroups, for example) is to downsize your server count though hardware emulation.
The emulation of computer systems, more popularly known as "virtual machines" has been around for a long time. IBM pioneered virtual machine technology back in the 1960s as a way to allow its customers to retain their investment in software by allowing emulation of entire computer systems to run on their latest hardware. On a smaller scale, virtual machines have been used for years in everything from USCD Pascal to Java, allowing programmers to write software for one set of APIs that has the capability to run on multiple hardware platforms. For our uses, we're interested in figuring out how to use one or more virtual machines to run a number of different operating systems on one physical box.
Most people have heard of VMWare and its virtual machine for emulation of desktop systems, VMWare Desktop. It's a great boon if you run a Linux laptop or desktop system but still need to run applications such as Visio or Microsoft Office. VMWare is a versatile performer. It allows you to run not only Windows (3.1 all the way up through XP), but you can also run Net/Open BSD or even another Linux virtual machine -- you can even run all of these at the same time.
One drawback, until recently, was that VMWare was a good desktop/laptop solution but it didn't scale to the enterprise. There are issues such as CPU performance and I/O bandwidth if you are trying to force a desktop machine (and VMWare Desktop) into server-level duty. Recently VMWare released new versions of its virtual machine software that can be used to run large-scale servers. The new enterprise versions of VMWare, called VMWare ESX and VMWare GSX, allow VMWare to be used for data center consolidation or departmental consolidation respectively.
The ESX version actually runs its own kernel and can host 4 to 20 Linux, Windows, or BSD virtual machines and supports 1Gb per second of network bandwidth. This is really an industrial-strength solution to support database machines and streaming content for those who want to cut down the number of physical servers they support in a data center while maintaining a single management interface.
The GSX version of VMWare is meant for departmental servers and runs on top of Linux (or Windows) and supports four to eight virtual machines. This is the perfect solution for businesses or departments that either have too many machines and not enough support staff, or have seen their IT budgets slashed and need to support more applications on disparate operating systems.
Once of the nice features of VMWare's enterprise solutions is their web-based interface that allows a system administrator to build and control all of the virtual machines from a single unified interface. This means that you can dispense with KVM switches and manage virtual machines right from your desktop.
VMWare's solutions are not cheap -- a VMWare enterprise license can run $2,500 -- but given the number of machines they can replace and the value they add in terms of being able to support more applications on your existing hardware they're quite a bargain.
David HM Spector is President & CEO of Really Fast Systems, LLC, an infrastructure consulting and product development company based in New York
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