I/O virtualization – last requisite to “full cloud” enablement

With virtualization (which became a data-center standard by the way), it’s no surprise that vendors are trying to the plate with products for virtualizing the complex I/O architecture. There are several mature products on the market that support IO virutalization but let’s check what is it all about.

In a conventional I/O environment (fig.1) each server can be loaded with many network cards and storage adapters. These physical I/O paths are generally meshed to storage switching equipment and conventional Ethernet switching. Uniform availability of the networks at each virtual host server ensures that virtual machines can migrate freely , finding preconfigured resources found there.

In the past, we had to make separate virtual switches on each virtual host and map them to real network ports on the back panel. If these switches and the  physical configuration were not reliably and homogenously configured, we ran into serious trouble during host-to-host machine migrations.

Figure 1

Suddenly, you could have let’s say 50 virtual servers loading a single gigabit switch port. What’s more, these servers may be mobile, and can transition from one switch port to another.  Furthermore , there’s a complete loss of debugging visibility from the network side. Even with the present generation of sophisticated on-switch troubleshooting and monitoring tools, that much variable I/O across a single Ethernet port makes it impossible to perform serious hardware-side troubleshooting. It’s often impossible to get a truly isolated picture of the actions of a single virtual machine. And even if we do get down to the most granular level, there’s no guarantee the machine will occupy the switch port we’re sampling off in the near future.

So what’s the resolution of this problem ? Look at figure 2 regarding non-specific virtualization of I/O resources with Infiniband.

Figure 2

Virtual I/O may be the final infrastructure element for the enablement of true cloud computing. We can already provision servers and storage resources dynamically the only truly physical constraints remaining are hardwired physical I/O requirements. By virtualizing servers, storage and now I/O resources, we finally make it possible to generate and provision networks completely on the fly and manage them appropriately.
In general, virtual I/O provides substantial benefits, including:

- Simpler management

- I/O resources portability

- Cost savings

- Fast and dynamic provisioning

- Lower physical “hardwired” constraints

Above advantages are counterbalanced by following potential concerns :

- Vendor drivers

- Lack of common standards

- Very little market penetration and testing – especially in universal (or non-specific IO virtualization)

What will be the next step of putting up to cloud computing ??