SWsoft’s Virtuozzo was a hit in the InfoWorld Test Center labs. It handles large numbers of virtual servers running on a single host system, and sports a great suite of management tools and open APIs to make automation simple.
Virtuozzo doesn’t quite compete with VMware or Microsoft’s offerings because it doesn’t offer hardware emulation, but this allows it to scale much more than the others, providing potentially hundreds of virtual servers per physical host. Thus, the main audience for Virtuozzo and other host-based virtualization products is in large-scale Web and application hosting environments and some QA applications. Virtuozzo’s approach is similar to that of Solaris Containers and BSD jails in that a single instance of a modified OS kernel supports multiple VPSes (Virtual Private Servers). Virtuozzo for Linux supports multiple flavors of the free OS. It can be installed on a Red Hat, Fedora, or CentOS platform, and can host VPSes running any of these Linux flavors, including Suse Linux Enterprise Server 9 and Debian, though they all share a single kernel. On the other side of the fence, Virtuozzo for Windows offers similar functions but can run Windows 2000/2003 VPSes.
Of course, Virtuozzo’s shared-host design means every VPS running on a given server must have the same basic OS kernel configuration. Therefore, the requirements of the applications and services to be run on the VPSes will dictate whether this approach is right for a given situation.
Performance of VPSes under Virtuozzo is quite impressive, with overhead of less than 3 percent in most instances.
In addition, the Virtuozzo management tools are extremely complete. They allow admins to customize minute details of each virtual server and monitor individual servers for performance, and they provide a thorough alerting and reporting foundation. Because Virtuozzo was designed to handle large numbers of VPSes per physical host, the management tools are designed to handle large numbers of server builds as well as dynamic application installation.
The task of building 20 servers is as easy as selecting a predefined template and specifying a starting IP address and a few other global configuration options. Within minutes, all 20 servers are built and available. Installing applications across multiple VPSes is equally simple, requiring only a drag and drop. All application templates are built from RPMs or file trees, which makes creating custom templates easy. The API for integrating custom code with the Virtuozzo back end is also quite complete, offering a very simple path to fully automate VPS creation and modification.
In addition to the Virtuozzo commercial product, SWsoft also supports an open-source version of Virtuozzo called OpenVZ that can be freely downloaded. This version lacks Virtuozzo’s great management tools, however, and it’s this benefit that makes the Virtuozzo solution a real winner.