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Bill Roth, Ulitzer Editor-at-Large

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Software-defined Storage and Software-defined Networking: A History

Much is said and written recently about software-defined networking (SDN) and software-defined storage. Both heavily depend on the new virtualization capabilities and can together be conceptualized as follows:

software defined storage v2

Hardware virtualization goes way back to the early 1970s and may be even 1960s. IBM mainframe virtualized hardware in the 1970s. VMware started in the 1998...

Over the past years we’d witnessed 3 generations of network virtualization: first, "direct" hardware virtualization – for instance, physical NIC or a disk accessed via the corresponding driver's emulated counterpart inside the VM.

Second, network virtualization - think “vSwitch”.

The year 2012 is the year of the 3rd generation of network virtualization – virtualization of the network services. Case in point: Nicira - see for instance:

http://blogs.vmware.com/console/2012/07/vmware-and-nicira-advancing-the-software-defined-datacenter.html

Storage virtualization underwent the same exact 1st generational phase and had somewhat stumbled at the second, ending up with (just) virtualized local block level access. Multiple intertwined historical reasons for this “stumble” are outside the scope and may well be part of the future fascinating book on high-tech in the first decade of 21st century.

Currently we are starting to see the first signs of the 3rd wave of storage virtualization, with the advent of VSAs providing local or localized access to { block and file and object } services for the virtual machines and their vApps. There are several underlying trends that make it simultaneously possible and feasible.

First, a dedicated VSA can do block and file and object storage much better than the hypervisor itself simply because it packs 20+ years of storage stacks development and, in many cases including Nexenta, many years of commercial deployment.

Second, VSA can hide the fact of local/remote storage from the VMs, thus providing an additional (and higher!) degree of virtualization. The hypervisors do virtualize local storage hardware. VSAs on the other hand do virtualize the entire storage, local and remote. (Think: scalability.)

Thirdly, VSA being a VM is mobile itself, and it therefore can follow (or rather, be followed by) migrating VMs using it for storage - to their (the VMs) new destination. This in turn creates a design and implementation opportunity to make VM migration a truly self-contained transaction, independent of the location of physical storage hardware (ie., the disks).
    
The 3rd gen of storage virtualization is happening now. Nexenta is in the midst of it, positioned to contribute to the wave and ride it as well.

Read the original blog entry...

More Stories By Bill Roth

Bill Roth is a Silicon Valley veteran with over 20 years in the industry. He has played numerous product marketing, product management and engineering roles at companies like BEA, Sun, Morgan Stanley, and EBay Enterprise. He was recently named one of the World's 30 Most Influential Cloud Bloggers.