> As far as I know MS doesn`t recommend that. Does NetApp support it?
I don't think MS cares (at least I haven't heard of such advice). It's definitively not a good idea to put apps on a share of a poorly performing or unstable file server - if it goes down or fails to deliver, all app servers would fail even if they had fancy clustering and load balancing for HA.
But the A300 is a good and fast NAS. Also, look at SMB 3, it's much more reliable than SMB 2.1 or earlier. You can even run some databases that way.
I can't speak for NetApp on support for specific apps, but to ONTAP those are just files - read requests come, we serve them according to the protocol specs.
On ONTAP controller (or any file server) failover, SMB clients have to reconnect so that may be where some apps (depending on the app and SMB client implementation) may get confused, but SMB 3 is quite good in that regard so I'd look closer into this particular area and maybe give SMB a try.
I think nothing prevents you to also consider iSCSI - you can copy the same binaries to a "gold" volume and make N clones of it to present eac to one of of N app servers. There would be no protocol concerns and contents of N volumes would be deduplicated if deduplication is enabled on A300. Some folks prefer to unmount + clone + remount clones but you could also use NetApp XCP (https://xcp.netapp.com/) to just copy data from one source to N destinations.