The VMware software-defined storage strategy focuses on a set of VMware initiatives regarding local storage, shared storage, and storage and data services. Software-defined storage is designed to provide storage services and service level agreement (SLA) automation through a software layer on the hosts that integrates with and abstracts the underlying hardware. With software-defined storage, virtual machine storage requirements can be dynamically instantiated. There is no need to repurpose LUNs or volumes. Virtual machine workloads might change over time, and the underlying storage can be adapted to the workload at any time.

A key factor for software-defined storage is Storage Policy-Based Management (SPBM), which was first featured in the VMware vSphere® 5.5 release, and can be considered the next generation of VMware vSphere storage profile feature. Storage Policy-Based Management offers a critical component for VMware in implementing software-defined storage. Using SPBM and VMware vSphere APIs, the underlying storage technology provides vSphere administrators with an abstracted pool of storage space for virtual machine provisioning. The technology’s various capabilities relate to performance, availability, and storage services such as replication. A vSphere administrator can then create a virtual machine storage policy using a subset of the capabilities required by the application running in the virtual machine.

At the time of deployment, the vSphere administrator selects the virtual machine storage policy appropriate for the needs of that virtual machine. SPBM pushes the requirements down to the storage layer. Datastores that provide the capabilities included in the virtual machine storage policy are made available for selection. So, based on storage policy requirements, the virtual machine is always instantiated on the appropriate underlying storage. If the virtual machine’s workload changes over time, a new policy with updated requirements that reflect the new workload is applied.

Storage Policy-Based Management plays a key role for vSAN because its policies are applied granularly to a virtual machine’s virtual disks stored in the vSAN datastore. SPBM policies define which features of vSAN are applied to individual virtual disks.

 

For further information about the VMware software-defined storage model, see The VMware Perspective on Software-Defined Storage white paper at https://www.vmware.com/files/pdf/solutions/VMware-Perspective-on-software-defined-storage-white-paper.pdf.