VAAI is a storage-compatible feature. So first check with your vendor whether your storage is VAAI supported or look at VMware HCL for that.

However, you also need to check the vSphere side to see if it is enabled there as well. By default, it is enabled on the ESXi host:

1. Open VMware vSphere Web Client.
2. In the Inventory pane, navigate to the ESXi host.
3. Click on the Configure tab.
4. Under System, click on Advanced System Settings.
5. Search for DataMover.Hardware.
6. Check the value of the DataMover.HardwareAcceleratedMove setting and that should be 1.

7. Check the value of the DataMover.HardwareAcceleratedInit setting and that should be 1:

8. Click on Edit to change these values if required.
9. Search for VMFS3.Hardware.

10. Check the value of the VMFS3.HardwareAcceleratedLocking setting and that should be 1:

11. Click on Edit to change these values if required.
12. Repeat this process for all the ESXi hosts connected to the storage.
13. If you are using VAAI-capable/supported storage, then you can see this status in vSphere Client by following the proceeding steps:
    1. Log in to vCenter Web Client.
    2. Select Hosts and Clusters on the home screen.
    3. Navigate to an ESXI host.
    4. Click on the Configure tab.
    5. Navigate to Datastores in the Storage section.
    6. Check Hardware Acceleration Status. It should be Supported. If the Hardware Acceleration column is not shown, right-click on the column header, select show/hide columns, then check Hardware Acceleration: