Server Virtualization in Action: A View From the Trenches Page 3

By Amy Newman (Send Email)
Posted Dec 30, 2009

Deploying Server Appliances

Related to dedicated virtual servers are server appliances. Server appliances are open source (usually) VMs created for a specific function. They are downloadable VM images that serve as web database servers, blog servers, content management system application servers, and even file and print servers, to name a few. They are designed to be smaller and to perform a singular function, which makes them perfect candidates for projects that would otherwise require a physical system that would likely be underutilized.

Server Appliances are ready to use as soon as they’re downloaded, unzipped, and opened in your virtualization software console.

Table 9-4 lists some sites from where you can download server appliances.

Note: Server Appliances must be subjected to the same rigorous security sweeps and pruning as other servers. Don’t trust them just because they are prepackaged.

Adjusting and Tuning Virtual Servers

The next item of business you’ll need to tackle for your dedicated VMs is adjusting and tuning. You’ll need to do this after the system has been up and running for a few weeks so that you’ll have a feel for baseline performance. You need to monitor performance with a performance-monitoring tool such as Orca (

Tools like Orca give you a continuous (hourly, daily, monthly, quarterly, and yearly) view into system performance. Not only can you keep an eye on performance peaks and valleys, you can also determine the best times for backups and maintenance. You’ll also know when to add more RAM, more disk, more CPU, or even another VM to share the load.

So how do you tune a VM? The answer is, “almost the same as a physical machine.”


Adding RAM can be the easiest way to boost performance in physical and virtual systems. Your host system must have sufficient RAM for itself plus enough to run each guest efficiently and have room for growth. Often, but not always, adding more RAM can refresh sluggish systems. RAM is a cheap commodity and it has the highest performance boost per dollar of any performance enhancing adjustment. However, RAM is not always the culprit, as Chapter 12, “Form-Factor Choices and Their Implications,” will discuss, and adding RAM without knowing the root cause could have little impact.

Virtual Machine Add-ons or Tools

Adding your chosen platform’s VM tools is often ignored as a performance- increasing tweak. After installation, even before patching or updating, you should install the VM tools. Your overall experience with the VM’s performance will increase.

Drivers in these tools and add-ons boost and optimize video performance, as well as enhance mouse performance and transitions between host and guest, and deliver time synchronization improvements between host and guest.

Virtual Disks

Virtual drive configuration is also important. Stick with fixed-size virtual disks. Dynamic disks are nice to have, but you take a performance hit when using them. You can always add more disk space by creating another virtual drive for your VM.

Table 9-4  Websites Offering Downloadable Server Appliances.





Open source server appliances


VMware images of popular open source systems


Offering specialized open source server solutions


VMware and community server appliances

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