As Azure Stack is a fully integrated system and you really do not have to know all details of what is going on in the system in depth (as you will buy some kind of support as a service with the solution), it is always good to know some basic technology monitoring and troubleshooting steps in order to help the support team better when working on issues. For a dedicated look on Storage Spaces, I expect you to have a look at different experts who've published books on it.
Windows Server 2016 itself provides some basic monitoring tools for Storage Spaces Direct for the following:
- Quality of Service
- Storage Spaces health service (latency, throughput, IOPS, and failover clustering issues)