Take the following scenario:
A Storage Spaces volume is set up to store about a dozen or so .VHDX virtual disks used by running Hyper-V VMs. This volume is set up with some sort of redundancy. Each .VHDX file takes up 20GB-70GB of storage for a current total of 550GB.
Would it make any sense to use tiering on this volume with a 120GB SSD?
If tiering is at the file level, then there's a limited number of virtual disks that would ultimately get tiered.
If tiering is at some lower level, then it might be useful, as the entirety of any given virtual disk would not be rewritten on a daily basis.
I haven't been able to figure out how exactly the tiering mechanism works in that respect.