Introduction

The traditional storage array and SAN architecture have become objects of scorn in new data center constructs being shared by companies such as Nutanix and SimpliVity. There is truth to the fact that storage performance bottlenecks have been identified as root cause issues in many ways in recent years. There is also truth to the fact that the storage component in the legacy data center remains one of the most expensive and complex resource areas that face the IT department. The commoditization of flash storage has enabled opportunities for forward-thinking vendors to reconsider how storage is deployed and managed in the data center, leading to a number of innovative ideas that bring simplicity and lower costs to the data center. Such solutions include server-side flash-based cards, solid state disks used as cache, hybrid storage systems, and all flash arrays. While these solutions may handily address performance issues, another class of device has also managed to make significant waves in the race to the future of the data center: Hyperconverged infrastructure.

Enter software

While flash’s day has come, the market is also enjoying the rise of software as a defining component of data center architecture. VMware ushered in this trend so many years ago with software defined servers and today, this trend continues as the markets continue to develop software defined networks and software defined storage devices.

More and more, thanks to the sheer power of today’s hardware and an ability to leverage commodity hardware, software is being used to enable abstraction opportunities that lead to simpler, more flexible, and less costly service deployments.

VSAN is announced

This week at VMworld 2013, VMware publicly announced the availability of a beta of the company’s VSAN (virtual SAN) product, which is baked right into the vSphere 5.5 kernel, and for which general availability expected in the first half of 2014. VSAN creates a software-defined virtual array of storage by aggregating all of the local storage – both solid state and hard disks – from local vSphere servers into a single logical storage pool, which is then used for virtual machine placement. This abstraction layer can result in lower costs since much of the intelligence is moved from what would have been physical custom ASICs into software constructs and organizations can leverage less expensive disks for their storage environments.

VSAN has a number of characteristics that distinguish it as a possible “anti-SAN” choice:

• Scales up to eight nodes (tested) in current edition, but is likely to scale to a larger number of nodes as time goes on. It’s designed to scale to 32 nodes and will likely hit this target by the time it hits general availability. Each node can have up to 36 disks, so there is ample room for capacity growth.
• Built right into the vSphere kernel as a core service.
• Requires both SSD and HDD to be present, although not every server that leverages the pooled storage requires local storage. With both kinds of disks, VSAN leverages the SSDs for cache and the HDDs for storage. At present, both kinds of disks are required as persistent data cannot be stored on the SSD-based caching tier.

Learn about all of VSAN’s features here.

A lot to think about

There are a number of potential takeaway items from VMware’s introduction of VSAN:

• VSAN is far from a new idea, but it is a game changer. Other vendors (mentioned below) are doing similar things already and are further ahead in their efforts. In addition, there are a number of virtual storage appliances (VSAs) on the market that appear to perform a similar task, but many of these are targeted at smaller deployments than is intended for services such as VSAN.
• The release of VSAN is a strong validation of the hyper-converged infrastructure space. VSAN is a game changer for this reason. Nutanix, SimpliVity, and Pivot3 should be pleased with the announcement on this basis. This concept of ensuring that compute, storage, and RAM are all very close to one another while also being eminently scalable is gaining traction.
• SAN vendors may be at risk as mindshare begins to shift away from traditional shared storage systems back to local storage. Unlike local storage in the old days, VSAN and customers of hyper-converged systems don’t need to worry about local storage being stranded and unusable for the organization.
• Given the fact that EMC owns VMware, questions may arise regarding EMC’s willingness to watch VMware potentially erode EMC’s sales, should that ever begin to happen.
• VSAN is missing some enterprise grade storage features, such as deduplication. Other more mature solutions already support this common feature to differing degrees.

One of these is not the same

At VMworld, a number of attendees have compared VSAN to companies such as Nutanix and SimpliVity. However, that comparison seems a bit incomplete as it would seem to reduce the value-add for those two players to one based solely on storage when they bring much more to the table, of which storage is but one aspect.

Companies like Nutanix have been working on scale-based issues around convergence for years and have developed solutions that target individual issues and ensure the best possible performance. For example, Nutanix’s shipping product includes intelligence that keeps appropriate information local to the host in order to minimize the need for virtual machine storage I/O to traverse the network. While this may seem trivial, this feature is an example of the engineering efforts that have been put into fully released products on the market. VMware VSAN will have to spend time catching up.

Is hypervisor lock in a bad thing?

In addition, there is often a desire to avoid vendor lock in. This may become increasingly important in organizations that want to maintain the ability to move services to new vendors when it makes sense. VMware’s VSAN is a vSphere-only service. If a company wishes to move to Hyper-V or implement a separate resource silo for Hyper-V, it can’t be based on VSAN. Nutanix, on the other hand, takes a hypervisor-agnostic approach to the data center, with a software management layer that can fully abstract the hardware and the hypervisor so that customers can dictate software choices rather than having them imposed upon them by a software limitation.

In other words, with other solutions on the market, customers aren’t locked in to VMware and can freely choose the hypervisor most appropriate to their needs or create hypervisor islands, should that be desirable for some reason. Of course, VMware remains the strongest player in the data center with Hyper-V a very distant second. Although Wikibon’s survey would suggest that VMware’s share of the virtual workload market will drop over the next 18 months, the company will still control 68% of the virtual market to Hyper-V’s 16%. As such, vendor lock in at the hypervisor level may not be a major issue for the foreseeable future, making the VSAN service a reasonable choice.

For those not locked into a hypervisor, a decision to change hypervisors doesn’t mean a complete rearchitecting of the data center. Having the ability to abstract even at the hypervisor level means less disruption when hypervisor changes are made. The very fact that VSAN is tethered right into the vSphere kernel may be too stringent a physical tether for some.

Key points

As mentioned, VSAN is not a revolutionary new technical achievement. However, it is revolutionary in that it ratifies what is already happening in the market and is VMware’s endorsement of software defined storage. Such solutions bring much-needed simplicity and lower costs to the enterprise.

VSAN doesn’t displace other, more full-featured hyper converged infrastructure solutions, except maybe in the smallest of organizations. Other solutions on the market have years of intellectual property at their disposal that demonstrates their ability and the fact that they do more than VSAN. In addition, VSAN still relies on customers buying and managing individual servers, whereas Nutanix and SimpliVity provide a true all-in-one solution. The IP wrapped into these packages provides scale for all resources and they both have distributed file systems that enable advanced capabilities.

Action Item: CIOs that have been on the fence about hyper-convergence and software-based controllers should now jump off the fence. That market is here for the long-term and the benefits are real. Of course, this entire market is exciting right now and there are ample opportunities for customers to change the way they do business to enable faster go-to-market for new products, improve existing processes through better IT, and to lower costs.

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