What are the tools available to monitor Fortanix Appliance

Fortanix recommends Sensu monitoring tool to monitor CPU, Memory, Disk & N/W usage. Sensu Go is available for free, for more information you can visit Sensu website. 

The below article explains how to setup/configure Sensu and start monitoring Fortanix Appliances 

https://support.fortanix.com/hc/en-us/articles/360045907552-Fortanix-Data-Security-Manager-Monitoring-and-Alerting-Solution