I/O virtualization is a new form of virtualization that is justifiably gaining attention in the data center. It's one of several virtualization offshoots -- such as service virtualization or facilities virtualization -- spawned by the meteoric rise of server virtualization. But what is I/O virtualization, exactly? And what benefits can it bring to the data center?
First of all, I/O virtualization is a valid form of virtualization and not just some vendors' attempt to capitalize on the hot virtualization market. Beware of vendors claiming that their product also provides virtualization. In a lot of cases, the "new" virtualization is just marketing speak.
I/O virtualization is a very new market with some very new players. Therefore, it makes it difficult to discuss real-world scenarios in which I/O virtualization has been used because there just aren't that many. Two companies offering I/O virtualization products, 3Leaf Systems and Xsigo Systems are both very new companies, not too long out of stealth mode. Two more well-known companies, Cisco Systems and Brocade are also working in this space, but their products are not able to fully provide I/O virtualization services until some additional standards are defined.
Let's try to tackle what I/O virtualization is. In this context, I/O virtualization is the abstraction of upper layer protocols from physical connections or physical transport. This is accomplished in a couple of different ways. Some vendors, such as Xsigo and 3Leaf, use the relatively well-established InfiniBand interconnect technology as the physical transport layer, allowing them to leverage InfiniBand's extremely low latency and high bandwidth to carry TCP/IP, Fibre Channel (FC) and other traditional protocols. Other vendors, s
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uch as Cisco and Brocade, are banking on future standards such as 10Gb Ethernet or extensions to 10Gb Ethernet like Data Center Ethernet (DCE).
DCE is an in-progress IEEE standard that aims to provide greater efficiency, lower latency, lossless and error-free behavior and consistent behavior to Ethernet networks. These characteristics are common in today's FC-based storage area networks (SANs); bringing such capabilities to Ethernet networks will enable new services and new applications that would not have been previously possible. Fibre Channel over Ethernet (FCoE) is a prime example of this.
As a result of this abstraction, I/O virtualization vendors tout the benefits of greater flexibility, greater utilization and faster provisioning. To understand some of the benefits of deploying I/O virtualization, consider the following example of I/O virtualization deployment: a server virtualization environment using larger, rack-mount servers with about 6-8 network interface controllers (NICs) and two FC connections per server. A minimum of six NICs is typically recommended for VMware environments: for example, two for the Service Console, two for VMotion and at least two for virtual machine (VM) traffic. Deploying an InfiniBand-based I/O virtualization solution would have the following two effects in this environment:
These are just two potential effects of deploying I/O virtualization. Other potential benefits, as well as a couple deployment scenarios, will be the subject of a future article.
About the author: Scott Lowe is a senior engineer for ePlus Technology, Inc. He has a broad range of experience, specializing in enterprise technologies such as storage area networks, server virtualization, directory services, and interoperability.
