If you have installed to a newer version of ESXi on your Gen8 Micro Server and are now suffering from very low performance disk speed, try the following steps to downgrade to a former hpvsa-driver (scsi-hpvsa-5.5.0-88).

Just follow these simple steps:

1. Download the driver and unpack the archive named hpvsa-5.5.0-88.zip
2. Stop all VMs that are currently running on your machine.
3. Enable SSH connections to your server in the GUI
4. Copy „scsi-hpvsa-5.5.0-88OEM.550.0.0.1331820.x86_64.vib“ to the /tmp directory (just use WinSCP for that) – In my case, this file is 699 KB.
5. Start a Session to your server (using Putty)
6. change directory to /tmp
   
   cd /tmp

   1

   cd /tmp

7. Copy the vib file to /var/log/vmware
   
   cp scsi-hpvsa-5.5.0-88OEM.550.0.0.1331820.x86_64.vib /var/log/vmware/

   1	cp scsi-hpvsa-5.5.0-88OEM.550.0.0.1331820.x86_64.vib /var/log/vmware/

8. Start the „Maintenance mode“
   
   esxcli system maintenanceMode set --enable true

   1	esxcli system maintenanceMode set --enable true

9. Deinstall the running scsi-hpvsa driver
   
   esxcli software vib remove -n scsi-hpvsa -f

   1	esxcli software vib remove -n scsi-hpvsa -f

10. Install scsi-hpvsa-5.5.0-88
    
    esxcli software vib install -v file:scsi-hpvsa-5.5.0-88OEM.550.0.0.1331820.x86_64.vib --force --no-sig-check --maintenance-mode

    1	esxcli software vib install -v file:scsi-hpvsa-5.5.0-88OEM.550.0.0.1331820.x86_64.vib --force --no-sig-check --maintenance-mode

11. Restart your ESXi, stop the maintenance mode, disable SSH connections and start VMs again

Hope that helps for you as well.