Server-Side, Converged Storage vs. Shared Storage

As I discussed at a recent event and covered in one of our top-read articles, “How Will Storage Controller Technology Evolve in 2014?“, this may be a year of significant change in the way we architect storage. There are three things driving this change. The first is the rise of the Hypervisor (VMware, Hyper-V, Xen, KVM, etc…). The second is the seemingly endless supply of CPU power that allows virtualization to work. And the third is the widespread availability of Flash SSD. These three factors are forcing legacy storage architectures to dramatically change while enabling improved storage architectures to emerge.

The Rise of Server-Side Storage

While there are nuances between various vendor offerings, Server-Side Storage or Converged Storage essentially moves the storage software, the component that provides data services (volume presentation, snapshots, tiering/caching), into the same physical servers that are currently running the application workloads. These solutions drive down cost by eliminating the need for dedicated storage controller hardware and leveraging any available excess compute on the physical server itself. They will typically leverage internal storage in those physical servers as well, creating an aggregated pool of storage that can be accessed by virtual machines. There are a few that can keep all the data local and only use the aggregated pool for redundancy and VM mobility.

Fundamentally, there is nothing wrong with this approach and I have personally suggested to storage managers that they at least consider server-side storage as a potential solution to a variety of storage challenges they have. That said, I do have concerns with these architectures and those storage managers should be aware of them. No infrastructure is perfect, especially as it scales. Some of those problems were pointed out by my colleague Colm Keegan, in his article, “The Problems With Server Side Storage, Like VSAN“.

You can agree or disagree with any of the points made in that article. You may say that a given point is irrelevant because of some workaround. What’s important for me, and for Storage Switzerland, is that we brought some concerns to light and have given you something to consider instead of blindly heading down a path. We also have started what I think is a healthy conversation within the storage community about the different storage architectures you have to choose from.

What about the Problems with Shared Storage?

Let’s be clear, the reason server-side/converged storage solutions exist is that shared storage is not perfect, nor is it for every data center. Shared storage presents an upfront cost issue, a perceived complexity issue and potentially, a performance/latency issue. I personally don’t think the performance/latency issue is any worse than that of a converged solution that is presenting a volume aggregated across multiple physical servers. I also don’t see fibre channel storage as particularly complex, especially when comparing both environments at scale. But in full disclosure, I’ve been working with FC since it first came to market in the 90’s.

That said, when I sit down with an IT team to discuss the options for their storage infrastructure, everything is on the table to start. Then, as we learn more about their current environment and long term goals, we start pulling things off the table.

Which One is Best?

‘Which One is Best?’ is really only half the question. The question should really be “which one is best for my data center both now and long term”. There is plenty to like with both shared storage and server-side/converged storage solutions, and there are shortfalls as well. They both require upfront planning and they both will require careful attention to the network infrastructure as they scale.

Also the decision is not exclusively an either or decision. Just like data centers today have multiple types of storage systems, they more than likely will have a mixture of server-side/converged and shared storage in the future. There are also server-side solutions that can aggregate shared storage resources into their offering as we discussed in our article “Three Ways To Improve Software Defined Storage”.

You can search our site and see multiple articles that cover both sides of the debate. You can also reach out directly to one of our analysts for guidance, as literally, hundreds of IT professionals do each year. We open each of those discussions with the disclosure that we accept sponsorship from dozens of IT suppliers, many who compete with each other. That sponsorship allows us to participate in those end-user conversations and provide this website, with thousands of articles, blogs, webinars, videos, podcasts, on a wide range of technology subjects, at no charge to you, the IT professional.

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Twelve years ago George Crump founded Storage Switzerland with one simple goal; to educate IT professionals about all aspects of data center storage. He is the primary contributor to Storage Switzerland and is a heavily sought after public speaker. With over 25 years of experience designing storage solutions for data centers across the US, he has seen the birth of such technologies as RAID, NAS and SAN, Virtualization, Cloud and Enterprise Flash. Prior to founding Storage Switzerland he was CTO at one of the nation's largest storage integrators where he was in charge of technology testing, integration and product selection.

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