To integrate with the block storage arrays and to benefit from the array hardware operations, vSphere uses the ESXi extensions referred to as Storage APIs - Array Integration, formerly called VAAI.
In the vSphere 5.x release, these extensions are implemented as the T10 SCSI based commands. As a result, with the devices that support the T10 SCSI standard, your ESXi host can communicate directly and does not require the VAAI plug-ins.
If the device does not support T10 SCSI or provides partial support, ESXi reverts to using the VAAI plug-ins, installed on your host, or uses a combination of the T10 SCSI commands and plug-ins. The VAAI plug-ins are vendor-specific and can be either VMware or partner developed. To manage the VAAI capable device, your host attaches the VAAI filter and vendor-specific VAAI plug-in to the device.
For information about whether your storage requires VAAI plug-ins or supports hardware acceleration through T10 SCSI commands, see the vSphere Compatibility Guide or check with your storage vendor.
You can use several esxcli commands to query storage devices for the hardware acceleration support information. For the devices that require the VAAI plug-ins, the claim rule commands are also available. For information about esxcli commands, see Getting Started with vSphere Command-Line Interfaces.