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Thinking beyond one-size-fits-all virtualization
Virtualization is winning a lot of converts among datacenter administrators because of its ability to help consolidate IT infrastructure, improve manageability, and save valuable resources. Yet in a sense, virtualization has become a victim of its own success.
Due to the market share victories of certain vendors, virtual machines have become almost synonymous with virtualization in the public consciousness. But in reality, virtual machines represent a relatively small chapter in the entire virtualization story.
In the most basic terms, virtualization is about abstracting IT resources from underlying hardware. Often times, the impetus for a virtualization project is that it allows hardware to be treated as a shared pool or resource — and with a single interface that promotes centralized management.
On the systems side, virtual machines play a role in facilitating consolidation and high server utilization rates. But there are many other approaches of equal, if not greater, importance in an overall virtualization strategy.
Operating system virtualization software, such as Solaris Containers, is a powerful alternative to virtual machines. Hardware partitioning represents another example of an effective virtualization approach. Even compute grids can be viewed as part of a virtualization strategy because they offer a shared architecture that pools resources to transform the way applications are developed and delivered.
Storage virtualization also greatly benefits today's enterprises. Just as with server virtualization, it is possible to treat storage hardware as an abstracted resource that can be pooled and shared in order to lower costs, mitigate risks, and increase application service levels. As with server virtualization, a single interface into this abstracted environment vastly simplifies storage management and reduces complexity.
Server and Software Virtualization: One Size Does Not Fit All
In the server virtualization arena, virtual machines have recently garnered significant attention because of the success of companies like VMware and its ESX server. But virtual machines are not an ideal fit in every environment. In many cases, operating system virtualization better delivers on virtualization's promises of easier management, improved agility, and reduced costs. Therefore, it is important that customers know which virtualization technologies best address which parts of the datacenter.
Of course, the virtual machine landscape is more diverse than simply VMware and its ESX server. Logical Domains, Xen, Microsoft Virtual Server, LPARs, and DPARs have all assumed prominence as effective virtual machine technologies. Many of these strategies are tied to certain platforms: Logical Domains on Sun CMT servers, or LPARs on IBM server, or VPARs on HP servers, or Xen, VMware, and Microsoft Virtual Server on x86 and x64 servers.
But essentially, all virtual machines work the same way: They create an abstracted software layer, which acts like a mini-operating system that is booted first and essentially virtualizes the underlying hardware into little pieces, so different operating system instances run on the same physical server.
Virtual machines permit multiple operating systems (Windows, Linux, and the Solaris OS, for example), as well as multiple operating systems versions, to run next to each other on the same physical server. This makes virtual machines an ideal product for heterogeneous operating system environments, where different applications require multiple operating system types and versions.
However, the software in the virtual machine that does the translation (or, put another way, mimics the hardware) is expensive form a processing standpoint, especially in high I/O deployments. In fact, as enterprises add more virtual machines to a single server, the system overhead for running a virtual machine environment can quickly exceed 40 percent of the total available processing power.
If a particular application demands a lot of network or disk activity, virtual machines do not represent a good fit. But if the application has only modest network and disk requirements, virtual machines can be an ideal solution, particularly if the application needs to run on different operating systems or OS versions.
OS Virtualization: The Alternative to Virtual Machines
As an alternative to virtual machines, operating system virtualization occurs within a single operating system instance. Today, Solaris Containers and the Linux product Virtuozzo offer this kind of virtualization. By divvying up resources higher up the IT stack, operating system virtualization allows different application environments to share a single operating system kernel.
The benefits of OS virtualization include significantly less translation, essentially zero performance penalty, and reduced complexity because there is only a single operating system image to roll out and maintain.
The decision of whether to deploy virtual machines versus operating system virtualization boils down to how far down the IT stack an application needs to have isolation. The good news: Selecting a server virtualization approach doesn't need to be an either/or choice.
Enterprises can mix virtualization strategies and select the proper scheme for the right environment. For instance, a single server could house three virtual machine environments (one for Windows, Linux, and Solaris OS applications), and within the Solaris environment there could be hundreds of Solaris Containers — and the containers would operate with little added performance penalty.
Storage Virtualization: Finding the Right Mix
Much as in the systems world, storage virtualization has recently emerged as a way to address the availability, cost, and complexity challenges raised by today's storage environments. It is no secret that enterprises face the double-whammy of skyrocketing data storage requirements and flat IT budgets. On top of that, 24x7 data availability is more than a desirable goal — it's a business imperative.
To address these challenges, tiered storage strategies like information lifecycle management (ILM) have arisen to help balance cost and data availability by moving less frequently accessed data to less expensive media according to predetermined policies. While effective from a cost perspective, ILM strategies often contribute to complexity by encouraging a proliferation of devices and device types.
These challenges make storage virtualization a compelling concept because it can provide a single storage image and a direct interface to all tiers of storage resources operating in the background. Similar to server virtualization, storage virtualization creates an abstracted meta-layer that masks the complexity of the back-end architecture.
Storage virtualization delivers several compelling benefits to IT and business. It helps make the storage environment less complex by offering single pane management. It heightens the value of storage investments by promoting consolidation and greater utilization rates because the underlying storage is more effectively shared among applications. And it delivers improved data protection.
Storage Virtualization with Virtual Tape Libraries
As part of a storage virtualization strategy, a virtual tape library can reduce the complexity of the back-up environment. This approach creates a separate software layer between the host and the archive infrastructure to facilitate a seamless migration to tape without additional resources to manage the back-up process.
Instead of direct disk-to-tape archiving, virtual tape libraries perform disk-to-software-to-tape back-up based upon predetermined policies. In other words, virtual tape libraries keep the information most likely to be accessed resident on disk, enabling faster back-up and restore. Furthermore, they promote multi-volume stacking of tape cartridges for greater cartridge utilization and often resulting in a five- to 10-fold reduction in media costs.
Within the disk tier of a storage environment, virtualization helps reduces cost and complexity. That's because disk virtualization works by partitioning an array, so a number of servers feed into a single storage device. These storage domains maintain a logical partition between different applications' data that present virtually private storage to hosts, helping to prevent workload conflicts and ensure that applications are running at optimum performance.
Ultimately, disk virtualization delivers the advantages of more efficient and enhanced storage management — managing a single storage image, increased utilization, heightened availability, and better data protection.
To determine the right mix of storage virtualization products, enterprises need to assess their data storage and access needs by asking such questions as:
- How much data do we need to store?
- How much data do we need to back up?
- How available does the data need to be?
- Do we have a disaster recovery strategy in place?
For assistance is developing storage strategies, Sun Professional Services has a wealth of experience helping customers understand their storage environments and needs, assess possible solutions, and deploy the right mix of storage virtualization technologies.
Putting It All Together
Sun recognizes that no two enterprises are alike. Every enterprise has unique needs, application workloads, and data availability and access requirements. That's why Sun offers and supports a complete portfolio of server and storage virtualization software and hardware products.
Plus, Sun Professional services can help assess, deploy and implement the right mix of technologies and processes for any environment. In other words, Sun is committed to thinking beyond today's all too prevalent one-size-fits-all virtualization mentality.
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