VMware launched its virtual SAN (storage area network) in March 2014, allowing users to utilize storage within ESXi servers to partition their physical servers into virtual machines without the need for external storage. Companies looking to scale out virtual storage were excited by the prospect of vSAN (virtual storage area network) to deliver fast, resilient scale-out storage. Two years after the launch of vSAN, where is it today, and what do users think of it?
With the rollout of vSAN, VMware became competitive to storage array and software vendors. Server admins were looking forward to using vSAN because it gave them a symmetrical architecture that did not require external storage and thus made them able to use storage within existing servers. It also doesn’t require specialized storage skills.
However, no one solution can be all things to all enterprises, and as enterprises began to deploy vSAN across their environments, they noticed a big thing was missing.
vSAN and vNAS
That big problem? Despite its many benefits, vSAN lacks support for a file system.
The importance of having a file system within a data center cannot be overstated. Without a file system, the guest VMs (virtual machines) cannot share files between them and are forced to use an external NAS (network attached storage) solution as shared storage. Without a file system overlaying this data, it becomes laborious and impossible to scale efficiently.
And that’s not all. With the explosion of virtual environments across every industry, an enterprise setting requires support for hypervisors as well. Therefore, a scale-out vNAS (vitual network attached storage) needs to be able to run as a hyper-converged setup. As a result, a software-defined infrastructure strategy makes sense here.
In a situation where there are no external storage systems, the vNAS must be able to run as a VM and make use of the hypervisor host’s physical resources. The guest VM’s own images and data will be stored in the virtual file system that the vNAS provides. The guest VMs can use this file system to share files between them, making it perfect for VDI environments as well.
vNAS creates a flexible and scalable storage solution by being software-defined, supporting both fast and energy-efficient hardware, having an architecture that allows users to start small and scale up, supporting bare-metal as well as virtual environments.
Finally, a word about protocols. vSAN uses a block protocol within the cluster, but when designing storage architecture, it is important to support many protocols. Why? In a virtual environment, there are many different applications running that have different protocol needs. By supporting many protocols, the architecture is kept flat, with the ability to share data between applications that speak different protocols, to some extent.
Hybrid Dreams
More and more often today, organizations are storing data both onsite and in the cloud, a setup referred to as a “hybrid” cloud. By being able to use just the amount of cloud storage needed depending on the group’s needs delivers excellent gains in performance and flexibility. The challenge is that in vSAN, there is no file system that can be extended to cover the data in the cloud, and files cannot be shared between the onsite location and the cloud.
When a hybrid cloud architecture is based on vNAS, however, each site has its own independent file system. In a typical organization, different offices will need both a private area and an area that they share with other branches. As a result, only parts of the file system will be shared with others.
Setting aside a specific portion of a file system and letting others mount it at any given point in the other file systems delivers the flexibility needed to scale the file system outside beyond the office walls—ensuring that the synchronization is made at the file system level in order to have a consistent view of the file system across sites. Being able to specify different file encodings at different sites is useful, for example, if one site is used as a backup target.
Looking Ahead
Today, most of the world’s data centers are still using vertical scaling solutions for storage, which means that enterprises are seeking alternatives that allow them to scale cheaply and efficiently in order to remain competitive. vSAN offers speed and ease of setup, but it needs a bridge in order to be optimally effective in enterprise environments. vNAS is that bridge, creating a single file system spanning all servers.