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Is storage kicking servers in the battle of the bundles?

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Storage benefits

Then there are the advantages specific to the storage environment when it becomes part of a compute/storage/networking stack.

Converged infrastructure stacks deliver an elastic pool of storage resource that’s relatively easy to expand with minimal overhead and into which it’s possible to incorporate higher density storage mediums, such as Flash. A single enclosure can typically house multiple controller nodes and multiple enclosures can be clustered for backup and disaster recovery.

The software automation layer of the stack, meanwhile, typically enables it to handle the performance demands of file-level storage and the scalability demands of block-level storage.

Above all, there’s an important performance benefit to be gained over previous networked storage approaches because traffic remains within that enclosure, transferred over a shared backplane for lower latency and great speed.

“In part it’s a simple question of physical proximity: bringing storage disks closer to applications and to CPU and to reduce the redundant layers that exist between them,” says Robin Kuepers, storage director for Dell in EMEA. “A different internal switching architecture, converged on the backplane of a smaller form factor opens up the possibility of higher bandwidth and throughput.”

What is more, available storage capacity is used more efficiently, claims David Leyland, head of architecture, data centre and cloud at Dimension Data. “Even the smartest and most competent of IT teams struggle with storage management, not least in having the visibility into where everything is stored and where available capacity lies,” he says. “With a converged stack, all your available capacity is in one place and is visible through a single pane of glass console, so there’s inherent simplicity there. In our experience, it’s pretty common to achieve storage utilisation rates northwards of 70 per cent or 75 per cent with these products.” That compares with an average of around 20 per cent with networked storage arrays scattered around the infrastructure, he adds.

There’s also a benefit in terms of storage administration tasks, says Chris Johnson, EMEA vice president and general manager of HP’s storage division.

“I talk to a lot of customers and they just don’t want people in the IT department analysing levels of firmware between storage and servers and HBAs [host bus adaptors]. These are fairly low value-add activities. They want IT teams focusing less on engineering and more on what the business needs,” he says.

A new approach to convergence

While most of the large, established systems vendors have introduced converged stacks in recent years - most recently Dell with the VRTX tower for small and medium-sized business in July - a new breed of suppliers has also emerged that take a more storage-centric approach. These include Nutanix, Simplivity, Tintri and Virsto.

“Storage-centric design makes a fundamental assumption [that] it is easier to insert standardised servers into an optimised storage environment than it is to build a really good VM-optimised storage environment,” says Forrester analyst Richard Fichera.

By integrating server resources more tightly to a VM-optimised storage resource, these new products, he believes, “have the potential to radically change the balance of power in the enterprise infrastructure market by allowing vendors with strong storage offerings to rapidly encroach on the previously well-defended markets of established server vendors”.

In the case of Nutanix, its basic module is a 2U enclosure containing four independent 2-socket servers. Each module contains four system nodes, each with a 2-socket x86 node with 300 gigabytes (GB) of flash cache and 5 terabytes (TB) of user-visible disk on each node, giving a total of 20TB. All data communications between nodes, as well as between additional nodes that can be federated onto a single logical system, use a dedicated 10 GbE switch.

“This is truly software-defined storage,” says Dheeraj Pandey, CEO of Nutanix. “All our intellectual property is in software. We take simple hardware components with that software on top to make it just as good as any enterprise-grade infrastructure product out there with the benefit of getting rid of special-purpose storage appliances.”

Nutanix and its immediate competitors are largely early-stage companies and, for many enterprise IT buyers they represent a step into the unknown. But what they’re proposing shows such promise for reducing many of the barriers to effective implementation of a virtualised infrastructure and private-cloud computing, says Forrester’s Fichera, “that the rest of the industry will almost certainly be in hot pursuit”.

One overriding question remains, however, for those in charge of data centre infrastructure investments: to what extent does a converged stack from a single vendor, regardless of whether it takes a server-centric or storage-centric view, limit our future choices? In other words, what are the risks of vendor lock-in?

For many, those risks are a real worry - but maybe they shouldn’t be, according to Leyland at Dimension Data. “I’m not convinced much changes. Reduction of complexity always carries a certain amount of lock-in, but not necessarily a more than before. If you historically ran an EMC infrastructure for storage and you wanted to transition to HDS, it was pretty much a Grand Slam to make that happen. At least with blocks of converged infrastructure, you’re able to migrate block by block,” he says.

It’s a view echoed by Valdis Filks at Gartner. “To be honest, if you go out and buy a storage array from one vendor, you’re locked in for the next four to five years, because realistically, you can’t really get rid of it until you’ve depreciated it anyway,” he says.

Converged infrastructure buys represent a relatively minor element of overall data-centre investment, albeit a growing one, and most companies are still willing to buy and integrate ‘best of breed’ components. But vendor lock-in, he says, is to some extent an inherent risk of any IT procurement activity. “At least with a converged stack, you’re passing the screwdriver to the vendor,” he says. ®

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