Q. Can Storage Spaces use more than two tiers in Windows Server 2016?
A. In Windows Server 2016 there is a new storage solution in the form of Storage Spaces Direct which aggregates local storage connected to the nodes in the cluster and enables the storage to be used as cluster shared volumes via the Storage Spaces technology. With Storage Spaces Direct there are essentially three tiers of performance:
- Storage Bus Cache - Uses the highest performing storage available, e.g. NVMe
- Performance - Uses next highest performing storage with mirroring to provide resiliency, e.g. SSD
- Capacity - Uses the lowest performing storage with parity to provide resiliency, e.g. HDD
Note if you only have two types of storage then the highest performing is used for the cache while the other type will be divided between performance and capacity with the different resiliency option (mirror vs parity) providing the performance/capacity difference between the tiers. If you only have one type of storage then the cache is disabled and the disks divided between performance and capacity like the previously mentioned case.
For non-Storage Spaces Direct only two tiers of storage are supported like Windows Server 2012 R2, i.e. SSD and HDD, there is no cache. If you had NVMe storage that could be the "hot" tier while the rest of storage (SSD, HDD) could be the "cold" tier (you name the tiers whatever you want) but you cannot use three tiers.