There's all kinds of reasons for getting in to server virtualization, but VMware just added another one: storage simplicity.
It's kind of counter-intuitive how adding an abstraction layer can make things more rather than less straightforward because fundamentally virtualization technology is the opposite of "what you see is what you get." It involves dark magic and all kinds of devilry to turn one physical server into two, three or more virtual servers. Virtualization technology, in other words, is all about illusion.
But with the official launch of Virtual SAN — another devilish product that turns a cluster of servers into a pool of storage that can be possessed by virtual machines and controlled by storage policies — VMware has made life easier for those involved in the whole ritual of summoning virtual machines into existence and keeping them running.
"There is no need for a dedicated IT administrator to deal with vendor-specific storage intricacies," says Mark Peters, senior analyst at Enterprise Strategy Group. "An IT administrator can easily see the shared Virtual SAN storage resources, compute resources, and, most importantly, the defined storage policies, all from the familiar vSphere management interface."
Ben Fathi, VMware's CTO, delivers more good news. "You no longer have to deal with the underlying hardware, LUNs, Fibre Channel — you don't need to bother with that at all," he says.
How does this all work? Essentially the storage servers that make up a Virtual SAN all run VMware's vSphere hypervisor, and with Virtual SAN activated they can all be controlled centrally from vCenter. That makes storage administration just another chore that's carried out by the server virtualization wizards who administer the virtualized infrastructure through vCenter.
VMware's Virtual SANs are ready for the big time — they can scale to 4.4petabytes, offer 2M IOPs, and host up to 3,200 virtual machines on 32 server nodes. That's enough for some very big data centers.
The hypervisor is an interesting place from which to control storage as it is uniquely positioned in the software stack for visibility into the applications running on that storage, and also because it has a comprehensive view of the storage and other infrastructure involved, according to Pat Gelsinger, VMware's CEO. "It's the Goldilocks zone — it can see the application and infrastructure, and it is on the I/O path so it can execute the needs of applications on the underlying infrastructure," Gelsinger explains.
How Well Does Virtual SAN Work Outside of VMware Environments?
But there are still a few questions that need to be answered. For example, how does Virtual SAN work with a SAN you already have?
"It doesn't," is the simple answer, according to George Teixeira, CEO at software-defined storage (SDS) vendor DataCore Software. Unlike DataCore's SANsymphony -V software (for example), which can create virtual storage that supports existing SANs, Virtual SAN is only designed to work with VMware environments, Teixeira points out.
And how does Virtual SAN support presenting its storage to any other system other than ESX? Again, Teixeira says that the answer is that it doesn't — unlike SANsymphony-V, of course, which can work with any combination of hypervisor environments, plus the real physical world.
There's little doubt that VMware will bring its marketing muscle (and software expertise) to bear on Virtual SAN, and that plenty of VMWare customers will start using it. Probably much to the chagrin of traditional SAN vendors and administrators.
But Teixeira believes that there will be benefits for software-defined storage software vendors like DataCore as well. He's counting on the idea that once VMware has educated the market about the benefits of software-defined storage, enterprises will want to investigate other solutions that support heterogeneous hypervisor environments. Not to mention good old fashioned what-you see-is-what-you-get physical servers as well.
Paul Rubens is a technology journalist and contributor to ServerWatch, EnterpriseNetworkingPlanet and EnterpriseMobileToday. He has also covered technology for international newspapers and magazines including The Economist and The Financial Times since 1991.