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Network World - About seven Internet years ago (that’s roughly three weeks in the real world) I started discussing Parallels Virtuozzo Containers 4.0, an operating system virtualization product.
I got distracted (as is my wont), but now I shall continue where I left off, which was . . . oh yeah: I had the system running and launched the Parallels Management Console and created containers (virtualized operating system instances) from templates.
Templates are installed on the host operating system and provide predefined configurations of registry settings and applications to be used when creating a new instance of a container. What is really cool is that all of the settings and features of a container are shared by all instances that are based on the same template. This saves a lot of disk space and allows containers to be managed and reconfigured as groups based on the templates they were created from.
Template operating system parameters include CPU minimum, maximum, number of CPUs that can be allocated, disk space limitation, maximum memory use, maximum number of processes and kernel-level threads, maximum number of Remote Desktop Protocol sessions, default DNS and search domains, which virtual network adapters to use, offline services, traffic shaping, whether the container should run automatically on boot and so on.
This level of detail means you can create very closely constrained operating system environments and, not only can you fine tune the configuration of your virtual production servers, but testing your server configurations in marginal environments will be much easier.
Now, while being able to template operating system configurations is great, even better is the ability to template applications – in other words create a package of applications that can be added to a container without having to perform the installation process! This allows you to create a template for one or more applications and then apply it along with other application templates to a container defined by an operating system template.
The Parallels Management Console is a very powerful tool providing a single point to manage every virtual operating system on every server in your organization from anywhere. You can drill down into the configuration and performance of any virtual operating system, create, start, stop and suspend virtual operating systems, examine logs, and schedule and manage backups.
My only complaint with the Management Console is there’s not enough help in some areas, notably in interpreting log messages. Many of the error and warning conditions use non-obvious terms that aren’t covered in the Management Console’s help. On the other hand, there is a wealth of detail in the installed documentation on the Containers components and configuration files.
One of the most powerful aspects of Containers is that every management operation that is available in the Management Console also is available using a command line utility, so adding custom automation and management is fairly easy. There is even a facility for scripts that can be executed before and after many of the major operations on containers, such as starting, stopping or creating containers.