SDS Is More Than Just Virtualization

BullseyeToday, I read an article at SearchVirtualStorage entitled SDS a fancy way to say virtualization, says DataCore Software chairman.  In this article, DataCore Software Corp. chairman and founder Ziya Aral indicates that his belief is that SDS is essentially just virtualization and that he doesn’t really see the difference between the two terms.

SDS is a superset that includes virtualization

First, I understand where Mr. Aral is coming from as there are major similarities between the two concepts and people use the terms interchangeably and, let’s face it – vendors love to invent new terms all the time in a valiant effort to prove their forward-thinkingness and we’re seeing software-defined everything these days.  However, I see SDS is a superset technology that includes virtualization as one of its primary components.

I suspect that Mr. Aral and I probably think very much alike, but it comes down to semantics.  With that in mind, let me start the beginning.  First, there was virtualization.  But what exactly is virtualization in the way that we’ve come to know and love?  At its most basic level, virtualization is about abstraction.  Way back in the early 2000’s, VMware brought into the spotlight this now-common technology.  With virtualization, workloads are abstracted away from the underlying hardware and they operate inside what is a software-led construct called a virtual machine.

Abstraction is just the center of the software circle

But that’s the beginning and the end of “virtualization” as a technology—abstraction.  What comes next comes courtesy of additional software tools, such as additional capabilities built into the hypervisor itself as well as the additional capabilities bestowed upon the environment courtesy of management tools such as vCenter and System Center Virtual Machine Manager.

As I’ve said before, I consider VMware to be the progenitor of what could be termed software defined servers – yes, yet another software definition term, but when you think about it, it makes sense.  Virtualization plays the role of abstracting this software-based construct away from physical hardware, but it’s an additional software layer that really brings the magic and allows the advanced features, such as workload migration and raw intelligence.  Alone, the hypervisor – the specific service that provides virtualization – doesn’t go it alone.  In all cases, either the hypervisor has been imbued with additional powers beyond just virtualization or there are additional software tools that provide these advanced services.

It’s semantics, but important ones

In the context of software defined storage, I think this semantic delineation is really important.  Again, without virtualization, SDS simply wouldn’t be possible since SDS depends completely on the fact that storage resources are abstracted away from hardware.  Once abstracted, those storage services are then embraced and extended through additional software mechanisms.  It is these mechanisms that, for example, determine where to store files based on application need and that provide important storage services, such as deduplication, thin provisioning and other features used in the enterprise.  But, these mechanisms are not a part of the virtualization stack; they are additional services that bring additional functionality.  Another mechanism increasingly common in SDS is software that enables linear scale out capabilities.  Again, this feature relies on the fact that the storage is virtualized, but it’s an additional software component that allows the storage environment to meet the ongoing capacity and performance needs of the customer.

Software in a hardware world

Even in a “software defined” world, hardware remains a critical component.  However, when done right, the hardware becomes a relatively inexpensive commodity, just like has happened with virtual servers.  The same is happening with storage, but this is thanks to the ability for some software-based solutions to abstract (virtualize) those hardware resources and convert them into easily manageable software-based constructs that are then manipulated with various and sundry management tools.

In my view, the whole software defined world looks like a target with a bullseye right in the middle.  That bulleye represents the virtualization service with each subsequent ring representing additional software layers that enable the service.  So, v

Maybe it’s not that different

When it comes down to the end result, though, it really is all semantics and personal preference for how different technologies are viewed.  It easy to agree with this, though: Just like the internal use only shirts at DataCore say, “hardware sucks.”  Anything that can wring the cost and complexity out of such an important service as storage is a really important step forward in enabling nimbler, more focused IT.

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