The Proxmox answer to this is Ceph - https://ceph.io/en/
And how does Ceph/RBD work over Fibre Channel SANs? (Speaking as someone who is running Proxmox-Ceph (and at another gig did OpenStack-Ceph).)
You lose snapshots (but can have your SAN doing snaps, of course) and a few other small things I can't recall right now, but overall it works great. Have had zero troubles.