Pete Manca's Blog

Recently I talked about what I see as the next "waves of virtualization" taking the industry, I talked about I/O Virtualization as a key (maybe THE key) cornerstone, so I thought it might make sense to describe just what it is and why it's important.
Like all forms of virtualization, the physical world is masked and abstracted into a virtual representation, allowing for higher utilization or increased agility, etc. For IO, the physical world is typically defined by dedicated connections to Input/Output (I/O) devices such as disks, networks, CD-ROMs, consoles, etc.

In the enterprise, these devices can themselves be already virtualized (think Storage Area Networks) but their connectivity is typically very static – e.g. a fiber channel adapter connected to a specific port on a SAN switch.

I/O Virtualization abstracts the connectivity so the server itself is no longer statically configured to specific I/O wiring. This adds tremendous value to the enterprise. The most obvious benefit is that change management becomes easy. No longer do techs have to fish wire and re-wire data centers because server-to-I/O affinity has changed. With virtualization, the wiring stays static but the actual mapping between the server and the IO devices can be dynamic.

And this is just the beginning. I/O Virtualization also allows for easy server re-purposing, as a server can be “re-wired” to attached to different volumes on a SAN device or different networks, thus changing its personality or its life cycle (e.g. moving from test networks to production networks).

I/O Virtualization also enhances Server Virtualization, as it makes it easier for hypervisors to support migration – no need for clunky clustered file systems or open zoned SANs, which can expose serious security issues.

Taken even further, I/O Virtualization can help with Disaster Recovery. When the server is abstracted away from its I/O connectivity, it becomes very simple to move a set of servers (and their applications) to a remote site and quickly re-create the I/O environment. Something that can take weeks in the physical world can literally take minutes now.

So, hopefully you can see why I/O Virtualization is such a key cornerstone technology in the continued virtualization evolution. Be aware, though, that not all I/O Virtualization is created equal. IO/ Virtualization is not done by adding new layers of unmanaged hardware into the mix (think NPIV) and I/O Virtualization is not simply re-programming network and SAN switches as some would have you believe. It’s really about creating an agile abstraction layer that truly disassociates servers with their I/O devices, allowing for total flexibility in the data center.