How VMware wants to reinvent the SAN

VMware is out with Virtual SAN today, which aims to virtualize the storage layer

VMware has released a virtual Storage Area Network (Virtual SAN), which the company says will usher in a new era of policy-driven and virtual machine-centric storage provisioning.

SANs are typically made of disparate storage components aggregated to create a pool that can be tapped by compute resources. Traditionally, SANs have been set up using external storage boxes which are then controlled by a switch; they’re ideal for dynamic storage needs.

VMware is taking a different approach for Virtual SAN, however. Instead of using external storage arrays that are pooled, Virtual SAN is a software-only product that runs on x86 servers that an enterprise may already have. It creates the shared storage pool out of the internal storage resources of the servers. This means Virtual SAN can be deployed as an overlay approach without the need to invest in new hardware.

Virtual SAN also takes a somewhat novel approach to provisioning the storage. Traditionally, SANs have worked by setting up Logical Unit Numbers (LUN) or other connections between the storage and the compute. Instead, Virtual SAN is integrated directly in with the kernel of VMware’s ESX hypervisor. That allows virtual machines to dictate how much storage they need and then the Virtual SAN software automatically provisions it.

Users set templates or policies related to how much storage their VMs can request, how fault tolerant the storage should be (and therefore how many copies of it there will be) and what sort of performance it requires (solid state versus hard drive). Then, when the VM is spun up, Virtual SAN automatically provisions the necessary storage within the parameters of the policies that have been established.

Simon Robinson, research vice president for storage at the 451 Research Group likes the idea. “Our research has been telling us for years that IT and storage managers are pretty tired of all the complexity involved in managing storage – managing LUNs, volumes, RAID levels, etc., and server virtualization makes it even more so,” he says. “For organizations that are well down the virtualization path, having a VM-centric way of managing their storage makes a lot of sense.”

Virtual SAN has been in development for three years and in beta for about a half year, since VMware announced it at VMWorld 2013. In that time 12,000 customers have signed up for the beta. Ryan Hoenle, director of the non-profit Doe Fund, is a VMware compute virtualization customer and has been testing Virtual SAN in its DR platform. “It’s really a no-brainer when the hypervisor you want to use also includes this virtualized storage,” he says. Virtual SAN allows the Doe Fund to have redundancy where Hoenle needs it and not pay for redundancy where he doesn’t. “We get that same sort of flexibility from a storage perspective that we gained from a compute perspective when we went to VMware.”

VMware isn’t alone in taking this policy-driven and hypervisor-integrated approach to a SAN. Robinson notes that there are a variety of startups doing this as well, but they take a slightly different approach. Companies like Nutanix and SimpliVity offer converged infrastructure systems which combine other features such as deduplication, compression and sophisticated snapshots into their platforms, for example. Some startups also enable multi-hypervisor support. But, one advantage to VMware’s Virtual SAN is that it is “baked in” with existing VMware tools. “Virtual SAN represents a major validation of this approach, and that will be good for all players,” Robinson says.

With Virtual SAN, VMware is finishing off the trifecta of its software defined data center (SDDC) strategy. The company is already clearly established in the compute virtualization market with a leading platform there. It bought Nicira and is working on its network virtualization strategy. Storage can be thought of as a last frontier for VMware to conquer, and Virtual SAN is a piece of that strategy.

VMware spokespeople say that they don’t expect Virtual SAN to replace an existing SAN or NAS (network attached storage); they see it as a complementary platform that is especially helpful for use cases such as disaster recovery, test and development, and virtual desktops. It’s generally available starting today, priced at $2,495 as stand-alone software.

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