Software defined storage: the 'missing link'

23rd May 2013 | 07:00

Software defined storage: the 'missing link'

SDS can simplify storage management for businesses

VMware caught the IT industry's attention when it acquired software-defined networking start-up Nicira for $1.2 billion in July last year.

The move kickstarted the virtualisation giant's strategic rebranding around the 'software-defined data centre', which looks to virtualise all IT infrastructure so that computing, networking and storage can be delivered as a service in software to the business on demand.

Virtualisation has for years made it possible to consolidate server estates and find savings. After networking, attention has turned to storage, which stands out as one of the few remaining areas of proprietary technology in the data centre, according to 451 Research's Simon Robinson.

"Until recently, most high end storage systems ran on custom processors and even had specific networking connectivity in fibre channel," he says. "The consolidation of resources using virtualisation that's happened on the server side hasn't really reached storage yet."


Software-defined storage (SDS) takes the programming away from the hardware on which the stored data resides. The data is effectively pooled and its use in applications can be automated through policy-based management.

Because the programming is decoupled from hardware, it's possible to add low-cost commodity storage without breaking existing configurations.

Additionally, the use of open source software in SDS promises to end 'vendor lock-in' as businesses no longer have to purchase more expensive proprietary boxes from their existing vendor.

Of course, the technology has the backing of VMware, which predicts the market could balloon to $50 billion by 2016.

Aspects of SDS systems include:

  • Use of commodity storage hardware.
  • Simplified policy-based storage management spanning multiple arrays.
  • Simplified administration of storage.
  • Scale-out architecture.
  • Thin Provisioning and snapshots.
  • Open source software.

Beyond virtualisation

SDS has emerged from the shadow of the storage hypervisor. However, to qualify as a 'software-defined' solution, vendors must provide functions beyond virtualisation in their platforms, starting with a move to commodity hardware, says Robinson.

"The enabler of software-defined storage is that storage runs on off-the-shelf hardware, which is increasingly possible now and even becoming the norm," he says.

"Everybody has their own definition of software-defined storage, but that should be the first thing."

Sean Horne, Chief Technologist UK & Ireland at EMC, which last month announced its own SDS offering in ViPR, says SDS platforms should go further than virtualisation by introducing new, simplified ways of allowing IT managers to flexibly allocate storage to the business.

"Most storage hypervisors don't necessarily drive any of the other benefits that application owners want around flexible performance and being able to acquire storage on demand through a portal," he says. "Software-defined storage is much more about driving administrative simplicity."

Making storage simpler to manage could prove one of the most appealing aspects of SDS for small to midsized businesses, according to Ovum analyst Roy Illsley.

He says: "Software-defined storage has good potential for SMEs because the right type of solution will mean they won't need to hire people with specialist skills to manage storage."

Such functionality is more likely to be found in a SDS solution built with a converged infrastructure, he adds.

Illsley points to US SDS vendor Nutanix's Virtual Computing Platform, which combines storage and the compute power of a commodity x86 server into a single, integrated system. If the business needs to scale out, more systems can be added over time.


"Rather than having separate islands of SAN and NAS, a CIO of an SME should buy a unit that is server-like in admin and management but provides the flexibility of completely pooled storage and compute," he says. "That will allow them to slice and dice both how they want."

He adds: "Nutanix does that, and it's a better option for SMEs than what's currently coming out of the major software-defined vendors because they would be severely restricted by the cost and newness of such solutions."

Alan Campbell, Regional Director of Western Europe at Nutanix, says the Virtual Computing Platform, which can be deployed by a non-specialist in half an hour.

"It was designed to be easy to setup, and if an SME required more IT infrastructure to support its business success after the initial deployment, it would then have an architecture that could do that," he says. "Equally, having a converged solution allows you to give as little of your real estate over to IT infrastructure, which reduces power consumption and physical footprint so that the business can use floor space for more customer-facing activities."

Open source has been put forward as a critical element of SDS by some vendors, including Red Hat, and US startup Nexenta, which maintains that it is required to end vendor lock-in by keeping storage systems open and flexible.

"Open source is one aspect of software-defined storage that we've highlighted as there certainly hasn't been an equivalent of Linux in the storage space, but there are some caveats," says 451's Robison.

Robinson explains that open source SDS platforms are currently having more traction with cloud service providers looking for a low-cost solution to compete with giants such as Amazon, as opposed to SMBs.

"In many cases, service providers just can't build profitable platforms on proprietary storage systems, so they're looking at the open source models," he says. "We may see open source trickle down to affect the wider enterprise, but I don't think smaller businesses should be concerned with it any time soon."

Better fit

For Robinson, SMBs may find a better fit in a traditional storage solution with the characteristics of 'software-defined' offerings.

"Smaller businesses may struggle with anything from setting up RAID levels and volumes to ensuring backups are completed and that a disaster recovery policy is in place," he says. "However, rather than software-defined storage, something of more relevance may be an appliance-based storage system that can still be 'defined' by software, where the value is still in providing a simple, easy to use mechanism in an off-the-shelf platform."

One such example of this can be found in Nimble Storage, he adds, which offers a data storage array that combines flash storage with a mechanical disk drive and uses software to intelligently serve applications based on their requirements.

"They've taken what is a complex and fragmented set of capabilities and boiled that down into one relatively simple architecture," he says. "Nimble don't describe what they do as software-defined storage, but it's certainly storage that's a system defined by the software that runs on it."

In terms of software-defined storage's future market direction, EMC's Horne believes it will ultimately take time before reaching speed.

"I don't think anything's going to dent the existing storage concepts for some time to come in a meaningful way," he says. "It's like moving workloads to the cloud. It's only accelerated in the last 18 months, which is evidenced by Amazon's growth in the amount of objects they're storing."

Horne adds: "Similarly. software-defined storage will bubble along before picking up and then it will go exponential."

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