What Appliances Should Be Virtualized?

In our last entry we discussed the value of virtual appliances and how they might be a better option for the data center than stand alone appliances are today. If you agree that there is value in leveraging the virtual infrastructure for appliances then the next step is to decide which appliances make the most sense to be virtualized.What we are looking for is appliances that are not using a lot of CPU and memory resources, which of course are at a premium in the virtualized environment. In the next several entries we will look at several categories of appliances that fit this category. The first may be a little surprising; virtual file services. While we often talk about high end NAS servers and using NFS for being the cornerstone of a storage infrastructure for server virtualization, it is not perfect for everyone. Some situations don't need a "NAS" they just need a file server.

For reasons we discussed in our article "A Case For Block Storage in Virtualized Environments" SAN storage is still the dominant storage infrastructure for server virtualization. One of the bridges to cross though is how to add file services to that configuration. There are the traditional options of adding a NAS Gateway or connecting a few general purpose OS servers to provide file services as well as probably the most common; buying a separate NAS. All have their various challenges, including cost, issues integrating and managing a separate platform as well as issues with flexibility of upgrades.

A virtual NAS appliance, as we discuss in our article "How To Add NAS Services To A SAN", can bring the best of all worlds if all you need standard file services. These appliances are not only lighter on resources than a general purpose OS they are also lighter on resources than a NAS. This is because they can leverage the virtual server infrastructure and not have to recreate the services that it will already provide.

In our testing the virtual NAS appliances can be installed and configured in a matter of minutes. All that has to happen is the virtual image is moved into place and the virtual machine started. Then a few networking questions are asked. Once that is done the NAS can be integrated into a directory structure or simply set up for manual user interaction. Time to install was less than 10 minutes. A stand alone NAS or general purpose server can't even be unboxed that fast.

The most important new capability that a virtual NAS appliance has is the ability to shift the file sharing workload to another physical host as needed. For example if performance became a problem the virtual instance could be shifted to a second system with more CPU and bandwidth without the need for reconfiguring the environment or installing additional hardware.

Virtual NAS appliances can dramatically reduce the amount of additional hardware that is needed in the data center and if all you need to do is add file services to an existing SAN should garner strong consideration.

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George Crump is lead analyst of Storage Switzerland, an IT analyst firm focused on the storage and virtualization segments. Find Storage Switzerland's disclosure statement here.