To enable VAAI support on ESXi using Synology NAS devices, you need to install the Synology NFS VAAI plug-in available at the Synology website.
vStorage APIs for Array Integration (VAAI) is an API framework that allows to direct some storage tasks directly to the datastore offloading the ESXi improving the performance.
Install Synology NFS VAAI plug-in
From the Synology's website download the Synology NFS plug-in online bundle in .VIB format.
Using a tool like WinSCP, copy the downloaded .VIB file to the /tmp folder on the ESXi host to configure.
SSH the ESXi by entering the root credentials. Run the following command to install the plug-in:
# esxcli software vib install -v synonfs-vaai-plugin-1.1-1004.vib --no-sig-check
When the installation has completed successfully, enter the host in Maintenance Mode to ensure no virtual machines are running on the host (if the ESXi is member of a cluster, VMs will be moved out from the host). Right click the host and select Maintenance Mode > Enter Maintenance Mode.
Now reboot the host to enable the new settings. Right click the host and select Power > Reboot.
When the host has rebooted, right click the ESXi and select Maintenance Mode > Exit Maintenance Mode.
Verify if the plug-in has been properly installed running the command:
# esxcli software vib list | more
In vSphere Client, select the Synology NFS datastore and go to Configure tab. Select Hardware Acceleration section to check the Hardware Acceleration status. The value is now set as Supported.
It's now possible to take advantage of VAAI capabilities for the Synology NAS used as NFS datastore.