ever since I upgraded my cluster to ontap 9.7 (currently 9.7P4), all luns allocated to vmware esxi hosts (all versions) appear as flash disks in vsphere even though the controllers are “regular” FAS with no ssds at all.
I don't have ONTAP 9.7 in production so can't really verify for you but in VMWare ESXi/vSphere you can mark a "disk" or "LUN" as "FlASH", indicating that the disk is an SSD (SSD/flash storage backed). However, as I am reading about it more, it says that if you mark Spinning Disk as 'Flash' it can seriously deteriorate datastore performance, so you have to be cautious.
9.7P4 is just released two days back "29-May-2020", so I wonder how many customers have upgraded to this version. Let's see if someone on this version can verify this for you. It may well be a 'bug' (Internal) ? No harm in raising a ticket with NetApp just to get this clarified.
Curious - If you provision another test LUN to ESXi from 9.7P4, does that also appear as 'SSD' ? Just to rule out any human errors on VMware settings side.
Yes, the VPD page reporting for block devices changed in ONTAP 9.7 to report as non-rotating (solid state).
When I investigated this for a customer in 2018, I found the performance issues were relevant to local host disks, not array disks. With ONTAP, the use of memory and caching mask the rotational characteristics of underlying disks, therefore Engineering made this change for all LUNs regardless of the physical disks used.
@konnerth : Thanks for sharing & confirming this information. Much appreciated. I think it makes sense, ONTAP is anyway 'write optimized' and along with flash it actually masks the underline disks ' performance (Even though one could argue that there is a 'significant' difference in latency to the 'End Application' when we compare all_flash SSD vs cached HDD aggr).