Server clusters and server virtualization may be two different animals, but they're animals that can work well together in a data center, says Hakon Bugge, founder and CTO of Scali Inc., a Linux clustering systems provider in Marlborough, Mass.
Clustering technologies connect many servers to increase computer power, and virtualization technology creates multiple, isolated server environments on a single machine. In this interview, Bugge explains how these two approaches can be used together, how to choose and provision servers for virtualization and why platform independence matters in virtualized environments.
When can server clusters and server virtualization technologies work in tandem in one environment?
Hakon Bugge: Clustering and virtualization technology working together can come in very handy in scenarios where one is running multiple applications with different requirements. We see that with the increase in cluster adoption and server consolidation, environments are becoming increasingly dynamic. It's no longer the norm that one runs a single application on a dedicated cluster.
Today, many users run multiple applications on their clusters. In some instances, one application may require a SLES 9 [SUSE Linux Enterprise Server 9] operating system and the others require RHEL 4 (Red Hat Enterprise Linux 4). Virtualization can offer a rapid alternative to reinstalling all of the servers.
What new server technologies are enabling a more rapid adoption of virtualization and why?
Bugge: Technologies from AMD and Intel are enabling more efficient virtualization at the hardware layer. Multi-core architectures are increasing the need for virtualization in order to maximize the utilization of the system.
Is platform independence a key consideration when choosing a virtualization software or hardware vendor?
Bugge: Every customer I meet claims that platform independence is a requirement in today's increasingly complex IT environments. This is particularly true as consolidation is bringing many different brands, architects and operating system environments into a single infrastructure.
One may have environments in which a hosted virtualization solution, such as Microsoft Virtual Server, is sufficient, but, in general, I'd recommend that one should focus on implementing solutions that offer the greatest degree of flexibility.
What are the top criteria for selecting servers for a virtualization implementation?
Bugge: Ensure that the server environment that you are considering has the capacity for expansion in the key dimensions for your application. While often people only consider CPUs as the key consideration, network specifications, including bandwidth and latency as well as I/O and memory, can have a significant impact on the efficiency of the solution.
Are blades absolutely necessary for server virtualization? Won't rack or tower servers work as well?
Bugge: Virtualization works as well on rack and tower server environments. The whole point of virtualization is that the application environment becomes isolated from the hardware platform.
Does a company have to use 64-bit servers to get the most from virtualization?
Bugge: You don't have to use 64-bit servers in virtualization environments but this is the architecture we see most often these days. Although 32-bit servers work, the amount of memory that you could use is a limitation, plus they don't offer hardware layer virtualization.
What is your pick for the best "best practice" for provisioning servers in a virtualized environment?
Bugge: The degree to which the provisioning capabilities are dynamic needs to be a key consideration in your virtualized environments. Dynamic provisioning technologies are rapidly evolving in enterprise computing and cluster markets and they allow hardware resources to be better balanced with evolving business requirements.
Virtualization technology clearly eases provisioning requirements in cases where servers no longer need to be re-provisioned, and can be more time consuming and leaves greater room for error, and are instead, virtualized.
Does virtualization make it easier for a company to migrate from proprietary applications to open source applications and proprietary operating systems to Linux?
Bugge: Virtualization can ease the migration to a certain extent. First and foremost, we see that virtualization makes it easier to start using and testing new applications. For example, the process of staging, QA [quality assurance] and development can be simplified.