Storage APIs is a family of APIs used by third-party hardware, software, and storage providers to develop components that enhance several vSphere features and solutions.

This publication describes the following sets of Storage APIs and explains how they contribute to your storage environment. For information about other APIs from this family, including Storage API - Data Protection and Storage API - Site Recovery Manager, see the VMware Web site.

Storage APIs - Multipathing, also known as the Pluggable Storage Architecture (PSA). PSA is a collection of VMkernel APIs that allows storage partners to enable and certify their arrays asynchronous to ESXi release schedules, as well as deliver performance‐enhancing, multipathing and load‐balancing behaviors that are optimized for each array. For more information, see Managing Multiple Paths.

Storage APIs - Array Integration, formerly known as VAAI, include the following APIs:

Hardware Acceleration APIs. Allows arrays to integrate with vSphere to transparently offload certain storage operations to the array. This integration significantly reduces CPU overhead on the host. See Storage Hardware Acceleration.

Array Thin Provisioning APIs. Help to monitor space use on thin-provisioned storage arrays to prevent out-of-space conditions, and to perform space reclamation. See Array Thin Provisioning and VMFS Datastores.

Storage APIs - Storage Awareness. These vCenter Server-based APIs enable storage arrays to inform the vCenter Server about their configurations, capabilities, and storage health and events. See Using Storage Providers.