Virtualization Coming of Age
Virtualization creates a logical abstraction of the physical computer hardware, allowing a single computer to appear and function as many virtual machines, each having its own view of the systems resources. Some virtualization products, notably Virtual Irons VFe, aggregate multiple machines into the appearance of one. Leading players in the virtualization arena currently include VMware, Microsofts Virtual PC, formerly Connectix; Sun Microsystems Inc.s Solaris Containers, formerly N1 Grid Containers (for OS sharing, not hardware sharing); and open-source initiatives including Xen."IBMs rHype creates partitions, subdivisions of a machine," said Illuminatas Eunice. "In a sense, its a very lightweight virtual machine ... much closer to the LPARS [Logical Partitions] in IBMs pSeries products." The difference, Eunice said, is that "while virtual machines tend to abstract a lot of the I/O elements of a system, partitions do much less of that. For example, in VMware, if you want to copy a VM from system to system, you can do so, and copy all of the files with it, the local storage files. That is harder to do in partitioning products, its not built in. So partitions tend to be about slicing up CPU time or memory, not about building an entire envelope to contain running applications." Some, like Microsofts, run only on Windows, and some, like Suns Containers, will only create more instances of a systems operating system, rather than allow a range of operating systems and versions. One of the new players, VFe, from Virtual Iron, is a data center virtualization solution that can aggregate multiple devices as well as divide individual ones. The experience of company founders includes work on Digital Equipment Corp.s VAX clusters and storage virtualization technology, as well as at Thinking Machines Inc., so the "carve many from one, combine many into one" approaches make perfect sense. "The problem that clusters and grids have is that they have to be made application-aware," said Alex Vasilevsky co-founder and chief scientist at Virtual Iron. "VFe hides the cluster and presents one single computer that consists of virtual processors, so you dont need to make them cluster- or grid-aware, or buy clustered file systems." There are even application-level virtualization tools, like Softricitys SoftGrid. For example, according to Raghu Raghuram, senior director of strategy and market development at VMware, which pioneered virtualization on x86 platforms seven years ago, "If you deploy an application on your Windows desktop, it makes changes to your registry. A second application may need to make competing changes. Softricity solves that by making a virtual registry at Windows level." For enterprises, whats significant is not so much any one of the recent announcements as the rapid speed and broad contribution into open virtualization, said Eunice. "Whether its Xen or rHype or Intels Vanderpool or AMDs Pacifica, everyone is focusing on getting virtualization to the masses." And companies large and small can benefit from virtualization of their servers and data centers, Eunice said. "The smaller the server, the worse the problems are for fault isolation and security breaches." Coming to the rescue: "Theres a whole class of mainframe technologies that will start to become available in the next two years. Virtualization will be a part of the solution ... youll be able to do partitions, virtual machines, and get good quality of isolation out of the box, and probably for a fairly low price as well." The result: "Better reliability, from a fault, failure and security point of view," predicted Eunice. "And much better utilization." "Virtualization is a powerful mechanism," said VMwares Raghuram. "Today, you can use it to turn your data center into one flexible compute pool. Another use is for more cost-effective disaster recovery. Because virtualization [with VMware] takes the applications and operating system, and abstracts them from the hardware, you can bring up a VM instantly, and you dont have to keep your primary and secondary hardware identical, which saves in operational costs." While consolidating servers brings benefits, "that was for a single box," said Nigel Dessau, vice president of Virtualization Solutions at IBM. "The question now is, how to do it across the enterprise." Next Page: Four stages of virtualization.
The various virtualization and partitioning technologies have similaritiesand differences.