HPE Smart Path may be causing you significant performance issues.
You should turn this off if you aren’t using enterprise SSDs. If you build an array it will be on by default, it will bypass your cache and this could give you a significant performance impact.
I have an RDS farm for 200 users. They use FsLogix profiles loaded from an REFS data store which resides on a RAID 10 array of SSDs, hosted on a server 2019 file server.
With HPE Smart Path enabled and all 200 users logged in, the drive hosting the profiles was Active time 100% and Disk queue constantly between 130 and 170.
When I disabled Smart Path and adjusted the cache configuration to include the array with the profiles, this immediately dropped to 30-100% active and queue 3-20, after about 5 minutes this dropped down to 0-40% active, queue between 0.1-10.
Potentially there are use cases where this works better, or maybe with very expensive enterprise SSDs it works well – for my deployment, it created very bad performance.