Preface

VMware Virtual SAN (VSAN) is the converged storage solution for VMware vSphere.

Integrated directly into the hypervisor, this is a native solution with no VM-based intermediaries for storage delivery. As a result, VSAN is fast, simple to deploy and manage, and integrates tightly with the existing VMware vSphere product suite.

As the solution is native to ESXi and runs on the hypervisor itself, its architecture is simplified and the storage-delivery mechanism is tightly integrated and uniquely suited to the needs of vSphere infrastructures. VSAN is an object-oriented storage solution, where each VM is comprised of a number of objects physically distributed across the ESXi cluster. This object-oriented nature means that access to your data happens natively, without the need for traditional intermediate storage protocols like iSCSI or Fibre Channel.

VSAN's object-oriented nature also means that your VMs exist as a series of distributed objects rather than a series of monolithic files. Whereas, with traditional storage, you have a series of files (configuration files, virtual disks, swap, snapshots, and so on), with VSAN you have a coordinated and related series of objects. These objects are a container for small configuration files (the namespace object, also called VM Home), objects for each virtual disk, objects for each snapshot, and an object for the VM swap space.

The key point when discussing VSAN's architecture, is how it integrates into the existing hypervisor infrastructure to deliver the final service of any hypervisor: production virtual machines. Behind this integration of the storage and compute virtualization layers is the notion of hyper-converged infrastructure. VSAN is one element of converged infrastructure. The goal of hyper-converged infrastructure is to abstract the traditional demarcations within the environment (compute, network, and storage) by converging all aspects of the datacenter into a software-defined model with a centralized control plane and a distributed data/IO plane.

VSAN is the storage element of the software-defined datacenter. User data (VMs) is abstracted and distributed across the compute cluster. Each VM exists as a collection of related objects, distributed optimally within the compute resources. VSAN natively integrates with vCenter and its associated management tools. As a result, VSAN brings truly native, truly integrated management of the storage system into the existing and familiar vSphere operating structure.

A major benefit to this new operating model of the storage system is its simplicity and centralized management. VSAN obviates the need for traditional monolithic storage arrays connected via traditional protocols. It also significantly improves on existing virtualization-centric distributed storage solutions, typically delivered as virtual storage appliances (VSAs). Embedding the distributed storage system into the hypervisor allows for gains in performance and management. Native management through the vCenter Server means that storage for the virtual infrastructure can now be deployed and managed by the virtualization engineer.