4.3.4 vSphere Storage APIs – Array Integration
vSphere Storage APIs – Array Integration (VAAI) is a set of protocol interfaces between ESXi and storage arrays. These ESXi extensions enable storage-based hardware acceleration by allowing vSphere to pass storage primitives to supported arrays.
In vCloud environments, cloning and snapshot operations stemming from provisioning tasks can quickly overwhelm the system. VAAI improves storage task execution times, network traffic utilization, and CPU host utilization during heavy storage operations.
For block-based storage systems, array integration extensions are implemented as T10 SCSI-based commands. Devices that support the T10 SCSI standard do not require a VAAI plug-in to offload storage functions such as full copy, block zeroing, and locking.
Hardware acceleration for NAS is enabled through the installation of vendor plug-ins. VAAI NAS plug-ins are developed by storage vendors and validated by VMware.
vCloud Director 5.1 supports the following offload via VAAI integration:
Block (FC, iSCSI): full copy offload to array (ESXi 4.1 or later, with supported storage array firmware listed in the VMware Compatibility Guide).
NFS: full copy offload to array (ESXi 5.0 or later only, with vendor supplied VIB (Virtual Infrastructure Bundle) installed on ESXi server).
NFS: Linked clone offload to array for storage arrays supporting clones of clones.