Head in the clouds

Sysadmin blog There are two major categories of x86 virtualisation; separate and shared kernel. Separate kernel virtualisation provides greater isolation at the expense of a small virtualisation overhead. Shared kernel virtualisation reduces the overhead required to provide containerised operating systems but with fewer barriers between instances.

There are a lot of x86 virtualisation products - and so a genuine need for cross-platform management products.

It’s early years yet, and the mergers between companies involved in this have not yet started. As a result, there is still innovation in this market and a lot of competitors trying to make a name for themselves.

One is Virtualmin’s Cloudmin. Cloudmin is a payware product belonging to the Webmin family. Webmin and Usermin are fully open source, Virtualmin is open core, and Cloudmin is closed. Joe Cooper, one of Webmin’s developers behind the Webmin family explains:

“I think our focus on the web hosting aspect of virtualization is sort of our guiding light here, and provides a pretty clear path forward most of the time. While most virtualization tools focus a lot on ease of starting up, ease of installing operating systems, etc., and a lot of that comes down to having a friendly desktop GUI. Cloudmin is much more focused on allowing delegation of resources to untrusted users, automating large scale operations, minimizing repetition when deploying many similar instances, automatically managing network setup, and doing it all with a comprehensive and easy-to-script API. And, of course, it also integrates smoothly with [the Webmin family] allowing moving websites and accounts from one virtual machine to another very easily.”

Cloudmin supports representatives from both separate and shared kernel virtualisation. If you are running Solaris, you are restricted to using Solaris Zones. If your host is Linux, your options are more varied.

For separate kernels, Cloudmin supports Xen, KVM and Amazon’s EC2. For shared kernels, there is support for OpenVZ, Vservers and Solaris Zones.

Cooper evangelises Xen:

“As a web hosting virtualization platform, it's pretty hard to beat, and pretty much every other option, including those we support and those we don't, has at least one obvious shortcoming in comparison.”

Virtualmin recommends that you use OpenVZ to support large numbers of reduced resource instances. For other workloads Xen’s support for paravirtualisation – and KVM’s lack of it – has made it a clear winner with Virtualmin. This support has obviously caught on, as despite all of the virtualisation platforms that Cloudmin supports, Xen has proven to be by far the most popular amongst Cloudmin users.

Cloud herders already familiar with Webmin will feel right at home with Cloudmin, because it retains the ease of use that has made the entire family so popular. Newcomers will find it easy to use, especially if they are seeking easy integration with other management applications designed to simplify the hosting and provisioning of web services.

The caveat: Cloudmin really isn’t aimed at all virtualisation tasks. I wouldn’t manage my VDI instances from Cloudmin, nor my collection of Windows servers. My Linux web farm, on the other hand, is a no brainer. When combined with the web and systems management capability of the rest of the Webmin family, Cloudmin has proven to be an unexpected pleasure. ®