VMware Inc. characterized its acquisition of storage software startup Virsto Software Corp. this week as a piece of its software-defined data center strategy.
Virsto refers to its software as a "storage hypervisor" because it sets out to virtualize storage the way VMware and other vendors' hypervisors virtualize servers. Virsto consists of a storage software appliance and a service that runs inside the hypervisor on the physical host, and promises to optimize block-storage performance, capacity utilization and provisioning.
Virsto actually supported Hyper-V first out of the gate in 2010, and added VMware support two years later. Virsto still has versions of its software for Hyper-V and Citrix XenDesktop, as well as VMware's vSphere.
VMware signed a definitive agreement Monday to acquire Virsto, but did not disclose the acquisition price.
In a blog post, John Gilmartin, VMware's vice president for storage and availability, wrote that VMware would continue to offer Virsto as a standalone product and support its customers while integrating its capabilities into future VMware products. VMware's press release about the deal said its parent company, EMC Corp., will also license Virsto technology for its storage products.
"Our customers have told us that managing performance and data services for virtual machines can be challenging, especially in I/O-intensive environments like virtual desktops," Gilmartin wrote in his blog post. "Virsto has developed a VM-centric storage management model that accelerates I/O performance for any block-based storage system, while providing efficient data services like VM snapshots and clones. These technologies have helped Virsto customers significantly improve the performance and utilization of their storage systems," he wrote.
The vision of a VMware software-defined data center was introduced at VMworld in San Francisco in August 2012, soon after the company acquired software-defined networking startup Nicira Networks for $1.2 billion. "Defining a new approach to storage will be a foundational element of the software-defined data center," Gilmartin wrote.
VMware storage performance challenges are well documented. Starting in September 2011, the company released a series of application programming interfaces that allowed third-party storage and backup vendors to integrate their products with the vSphere virtualization platform.
Then VMware released the vSphere storage appliance (VSA) in vSphere 5.1, which conjoined separate physical-server storage resources into a shared storage pool for virtualized applications. Now the company is adding Virsto's storage virtualization hypervisor to advance the vision of a VMware software-defined data center.
Hyperventilating over Hyper-V?
Russ Fellows, a senior partner at the Evaluator Group analyst firm, said the Virsto acquisition suggests VMware is looking over its shoulder at Microsoft. By building its Hyper-V hypervisor into its operating system, Microsoft has the potential to undercut much of VMware's value.
"Based on what I hear and who I talk to, VMware isn't afraid of any company except Microsoft," Fellows said. "Microsoft is the only company they really fear because of what Microsoft did to Netscape and other browsers. [Microsoft] took something that you could make money off [of], made it free and 99% as good; and all of a sudden, the market disappeared. [VMware is] worried about Microsoft doing the same thing to hypervisors."
According to Fellows, VMware is fighting Microsoft for every inch of the hypervisor market, and the Virsto acquisition was a preventive strike to eliminate a potential Hyper-V advantage. "[VMware] knows they've stayed ahead of Microsoft in every regard, with the exception of Storage Spaces in [Windows] Server 2012," he said. "I think they saw that as a potential advantage for Microsoft, and they didn't want Microsoft to have an advantage anywhere."
Storage Spaces is a new feature that enables thin provisioning of raw storage in the latest version of Hyper-V, allowing a virtual hard disk's capacity to exceed the underlying physical disk capacity.
Will software-defined storage neuter hardware arrays?
Mark Peters, a senior analyst at Enterprise Strategy Group, said the Virsto deal is an acknowledgement that storage is a big part of the data center convergence movement. "Years ago VMware said they were building the software mainframe," he said. "This is continuing that path. It's also an acknowledgement that storage is important. Although it's a relatively small acquisition, I think it has big ripples."
Not only are we seeing a software-led data-center technology convergence, Peters said, but also a movement of storage intelligence up the software stack. "I think storage functionality is going up the stack into server flash software," he said. "Whether it's called a storage hypervisor, an operating system or software-defined storage, it just makes sense to have the intelligence there."
If the storage hypervisor concept takes hold, it could devalue storage intelligence inside the array. "You could argue that storage is one of the last [data center] areas where hardware is really important," Peters said. "But if [the storage intelligence] sits in an operating system or in a hypervisor, then you probably don't need so much intelligence down in the storage system."
"I'm not suggesting that hardware becomes unimportant; it becomes differently important. This software still has to run on something and run something. It will be different hardware, far more about base reliability and price and less about the capabilities and functionality that we are used to having built in," Peters said.
Not everybody in the storage industry agrees with that assessment. Kieran Harty, who led research and development at VMware for seven years before he founded VM-aware storage array startup Tintri in 2008, said he views Virsto's storage hypervisor more as a crutch for legacy storage systems trying to keep up with virtualized environments.
"If you look at Virsto and the product they provide, it's essentially a cache in front of existing storage," said Harty, Tintri's CEO. "So, it still relies a lot on sophisticated functionality to be provided by the back-end storage. I view it more as an accelerator rather than a replacement for existing storage."
Tintri's VMstore appliance combines solid-state drives, hard disk drives and software built from the ground up for virtualized environments. It is one of a new wave of storage systems developed to run in heavily virtualized data centers.
Because VMware's hypervisor must work well with all major storage products, the best way to improve back-end storage performance on the hypervisor side is to put an I/O accelerator inside the hypervisor, Harty said. He sees the Virsto acquisition as a temporary step until VMware can deal with the performance and complexity issues. "I don't see this as an enormously strategic acquisition for VMware at all," he said.