Many organizations today are looking for ways to scale out their storage so that they can accommodate the data deluge. Virtual SAN (vSAN) enables users to employ storage in ESXi servers without the need for external storage, so when VMware launched its vSAN in March 2014, companies were excited. The company hoped this offering would be the solution to provide fast, resilient scale-out storage. Since its launch, what has developed and how are users feeling about it?
VMware set out its shingle as a competitor to storage-array and storage-software vendors when it rolled out vSAN. Server admins were looking forward to using vSAN because it gave them a symmetrical architecture that didn’t require external storage, enabling storage in existing servers. It also doesn’t require specialized storage skills. But no one solution can be all things to all enterprises, and as enterprises began to deploy vSAN across their environments, they noticed something big was missing.
Storage Alphabet Soup
Although it offers many benefits, vSAN lacks support for a file system. The importance of having a file system in a data center cannot be overstated—without one, the guest VMs cannot share files between them and are forced to use an external NAS solution as shared storage. Without a file system overlaying this data, it becomes impossible to scale efficiently.
What’s more, an enterprise setting requires support for hypervisors as well owing to the explosion of virtual environments across every industry. Therefore, a scale-out vNAS must be able to run as a hyperconverged setup. As a result, a software-defined infrastructure strategy makes sense here.
Where no external storage systems exist, the vNAS must be able to run as a virtual machine (VM) and employ 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.
Because it is software-defined, vNAS creates a flexible and scalable storage solution, supporting both fast and energy-efficient hardware, having an architecture that allows users to start small and scale, and supporting bare-metal as well as virtual environments.
Protocols require consideration as well. A vSAN uses a block protocol in the cluster, but when designing storage architectures, it’s important to support many protocols. Why? In a virtual environment, many different applications are running, having different protocol needs. By supporting many protocols, the architecture remains flat, having the ability to share data between applications that speak different protocols, to some extent.
vNAS and Hybrid Solutions
For an organization that has offices at multiple sites, each site has its own independent file system. It’s probable that different offices have a need for both a private area and an area that they share with other branches. So only parts of the file system will be shared with others. This common scenario, so essential to the functioning of a typical business, is impossible with a vSAN.
The hybrid cloud is a common occurrence these days, whereby organizations store data both on site and in the cloud. The ability to use just the amount of cloud storage that a group needs can deliver excellent performance and flexibility gains. The challenge is that in vSAN, no file system can be extended to cover the data in the cloud, and files cannot be shared between the on-site location and the cloud.
But each site has its own independent file system if the hybrid cloud architecture is based on vNAS. 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.
Letting others mount—at any given point—a particular section of a file system in other file systems enables the flexibility to scale the file system beyond the office walls, ensuring that the synchronization occurs at the file-system level to provide 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 serves as a backup target.
A Collaborative Storage Effort
With the tsunami of data that organizations now must address, vertical storage has become impractical for space and cost reasons. Enterprises are looking for ways to scale cheaply and efficiently so they can stay in business. vSAN has the advantages of easy setup and speed, but it needs a helper if it’s to work well in the enterprise. Along comes vNAS, which creates a single file system that spans all servers. This approach enables a consistent view of the file system across sites and a storage solution that positions enterprises for the future.
About the Author
Stefan Bernbo is the founder and CEO of Compuverde. For 20 years, Stefan has designed and built numerous enterprise-scale data-storage solutions that are cost effective for storing huge data sets. From 2004 to 2010 Stefan worked in this field for Storegate, the wide-reaching Internet-based storage solution for consumer and business markets, offering the highest possible availability and scalability requirements. Previously, he has worked with system and software architectures on several projects for Swedish giant Ericsson, the world-leading provider of telecommunications equipment and services to mobile- and fixed-network operators.