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August 18, 2006
• Vol.28 Issue 33
Page(s) 13 in print issue
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It’s A Virtual World
Server Consolidation For The SME
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 IT managers have a tough job: provide the essential services required for their companies, yet control and contain costs. As these essential services grow, virtualization as a server consolidation strategy has found increasing favor as a means of increasing reliability, scalability, and manageability while reducing the number of physical servers required to deliver these essential services. According to Robert Bradman, senior system engineer at Vente, “Once you go virtual, you will never want to deal with real servers again.”
 Virtualization In A Nutshell
For many SMEs, the prevalent model for server deployment is a large number of servers (each tasked with limited responsibilities), Web servers, DNS servers, etc. The original impetus for allocating services among individual servers was due to application incompatibility and the desire for redundancy. The result was a sea of servers overpowered for their tasks and underutilized. For IT, it meant lots of hardware to deploy, cool, and maintain.
Virtualization attempts to turn this model upside down. Products such as ESX Server from VMware (www.vmware.com), Xen from the University of Cambridge (www.cl.cam.ac.uk/Research/SRG/netos/xen), and Microsoft Virtual Server (www.microsoft.com) allow multiple VMs (virtual machines) to run concurrently on a host server.
Each VM runs its own operating system and its own applications isolated from the other VMs on the host server. As far as the VM is concerned, it’s simply a discreet computer, no different than any other on the network. From the host server’s perspective, each VM is an application that can be stopped, started, copied (cloned), or migrated to a new server.
Virtualization Benefits
Determining how many VMs you can run on a host server depends on the host server’s hardware and the requirements of each VM. It’s not unusual to run from 10 to 50 VMs on a single host server, assuming it’s provisioned with enough memory and has an adequate number of CPUs to provide virtualized computing power to the VMs.
One of the more popular servers used as a host is HP’s DL585 series (www.hp.com). Provisioned with four dual-core Opteron CPUs and stocked with 16GB of RAM, the DL585 can easily host between eight and 16 VMs, with each having the equivalent of a 1 to 2GHz processor and 1GB of memory. Comparing this 4U server to the 16U of rack space required for standalone servers, the data center savings become readily apparent.
Savings can accrue quickly, according to Bradman: “Virtualization has saved us tens of thousands of dollars in the first few months alone.” Not only does virtualization help minimize rack space requirements, it also lowers electricity consumption and the corresponding amount of cooling required.
Migration Techniques
If you need to migrate existing servers to a VM infrastructure (as opposed to creating virgin VMs), tools such as VMware’s P2V (physical-to-virtual) Assistant are essential. Simply boot the legacy server with the P2V CD, and it will copy the legacy operating system and applications into a VM hosted on an ESX Server.
Redundancy & Disaster Recovery
In addition to reducing costs, virtualization can also improve the reliability and survivability of key services for the SME. “In June our uptime was 100%. VMware’s product has their VMotion technology, which allows us to move live, running VMs to new physical hardware without interrupting the guest operating system, its network connections, or processes,” Bradman says. VMware also offers a high-availability service that can detect when a VM (or host server) has failed and seamlessly start a second VM on a different server.
The impact on disaster recovery is similarly impressive. If your data center becomes inoperable, VMs are much easier to deploy to secondary facilities because the host server abstracts the hardware layer. For example, a host server running ESX on an HP dual-processor server can run a VM initially deployed to an eight-CPU Dell PowerEdge (www.dell.com). No longer does your IT staff have to worry about the appropriate drivers or hardware components for each individual server. Simply install your backup copies of each VM into your secondary facility, and you’re back in business.
Gotchas
Although virtualization provides tremendous opportunities to improve your operations, there are some caveats of which you’ll want to be aware. First, be sure to plan your virtualization strategy properly; gather metrics from the systems you plan to virtualize so that you can adequately provision the host servers.
Also be sure to contact your application vendors to be sure there won’t be any support consequences when running applications in a VM. For many vendors, virtualization is a new experience, and they may not have the appropriate procedures in place to provide timely support.
Virtual Options
The increased adoption of virtualization is an ironic turn back toward computing’s origins. With the ability to virtualize almost unlimited VMs on a single hardware platform, the future data center may resemble the mainframe centers that were recently viewed as dinosaurs. 
by Chris Jackson
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View the chart that accompanies this article.
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