SPBM is an extension of the VM Storage Policies and the foundation of the SDS control vision from VMware. SPBM enables vSphere administrators to simplify storage provisioning and management, by assigning to each virtual machine the required storage features and capabilities. VM will be automatically provisioned on the right datastore that respects these requirements.

SPBM interprets the different storage requirements and dynamically composes the different storage services, like placing the VM on the right storage tier, allocating capacity, providing snapshots, replication, and so on. To understand storage features and capabilities, vSphere Storage APIs for Storage Awareness (VASA) could be used, but it's not formally mandatory.

In vSphere 6.5, storage policies are used widely, also for vSAN, VVols, SIOC v2, VM encryption (see Chapter 10, Securing and Protecting Your Environment).

Actually, you can consume policies from the HTML5 client, but you need the vSphere Web Client to build new policies. Depending on your configuration, there are some default policies built-in and used for generic datastores, vSAN, or vVols.

Please consider the following points:

• Policies are stored and managed by vCenter server, but can be applied to VMs in one or more clusters.
• Each vCenter in Enhanced Linked Mode has its own set of policies.
• A maximum of 1,024 policies can exist per vCenter server.
• The storage policy name can consist of up to 80 characters. Anyway, the storage policy name is not the true identifier because, like for VM names, a unique identifier is used instead.
• Storage policy can define one or many rules regarding performance, availability, space efficiency, and so on.
• Storage policies are not additive. Only one policy (that contains one or more policy rules) can be applied per object.
• A storage policy can be applied to a group of VMs, a single VM, or even a single VMDK within a VM.

To learn more, see this blog post—Understanding Storage Policy-Based Management at https://blogs.vmware.com/virtualblocks/2017/01/16/understanding-storage-policy-based-management/.