As the HP Z800 WorkStation comes with onboard 6-ports SATA Controller and 8-ports LSI SAS/SATA Controller, the existing LSI Controller was dedicated to VMWare ESXi v.6.7 thus leaving the SATA Controller unused.
For experiment purposes, I wanted to passthrough this SATA Controller to a VM for TrueNAS Scale use as Storage Pool and thus able to directly manage all the HDDs connected on this controller.
1. Firstly is to create a VM and install TrueNAS Scale and configure the network settings.
2. Next is to shutdown the TrueNAS VM.
3. In the ESXi Server Host, under --> Manage --> Hardware.
4. Look for --> Intel ICH10R 4-ports Controller --> Passthrough = Enable.
5. Put the ESXi Server Host into --> Maintenance Mode, and reboot the server.
6. After reboot, Exit Maintenance Mode.
7. Under the TrueNAS VM, right-click --> Edit Settings.
8. Click --> Add Other Device --> PCI Device.
9. A new hardware will be listed, ensure the new PCI Device = Intel ICH10R 4-ports Controller.
10. Boot-up the TrueNAS VM.
11. Login to TrueNAS, goto --> Storage --> Disks.
12. Now you should be able to see all the HDDs connected on that SATA Controller and proceed to create Storage Pool.
!!! HAPPY COMPUTING !!!