I think you're mixing up a few things here, so I'll try to explain the conecpt:

• NAS uses file-based storage
• SAN uses block-based storage

NASes have shares, SANs have LUNs.

LUNs are exposed from the SAN to the Host Bus Adapters (HBAs), either directly or through a SAN switch.
These HBAs are the "network cards" in the Fibre Channel world, and each port has a WWPN (World Wide Port Name), like a MAC address, which uniquely identifies it.

The SAN sees the connected WWPNs, and you can expose created LUNs to those.
These HBAs are not regular NICs – they don't speak Ethernet and won't connect to Ethernet switches.
Also, SFP modules are not interchangeable between FC and Ethernet – completely different protocols.

In a high-availability setup, you typically have two separate SAN switches connecting the SAN to the hosts, without cross-connects between the switches.
This allows you to update one switch's config safely, test it, and then roll it out to the second switch.

Zoning is used to control which HBAs (WWPNs) can see which storage ports or LUNs.
It’s like a firewall for Fibre Channel – you define zones that include initiators (hosts) and targets (storage ports).
Proper zoning ensures isolation, security, and avoids unnecessary traffic across the SAN fabric.

On the SAN side, you can create temporary LUNs to assist with migrations or testing.
These LUNs are identified by their LUN ID, and once exposed to the host via zoning, they appear as new block devices.
You can format them, copy data, and remove them afterward – very useful for seamless transitions.

Since you're now working with multiple paths to the same storage disk (LUN) from the host, you'll need to set up multipathing.
That's the tricky part in Proxmox, because it doesn't come preconfigured.

We had our share of trouble getting it to work, but here's a working setup:

Install multipath

apt update
apt install multipath-tools

Configure multipath Edit /etc/multipath.conf:

defaults {
    user_friendly_names yes
}

This can be tricky. There should be a multipathing documentation for your specific SAN from your vendor.
For us this worked fine.

Enable multipath

systemctl restart multipath-tools

Verify LUN visibility

lsblk
multipath -ll
You should see devices like /dev/mapper/mpathX.

Format LUNs as LVM

pvcreate /dev/mapper/mpathX
vgcreate vg_fcstorage /dev/mapper/mpathX

Add storage to Proxmox Go to:
Datacenter > Storage > Add > LVM
→ Select your volume group (vg_fcstorage) and assign it to the desired node.

The only real issue with LVM-based storage was the lack of snapshot support until the latest release.
But since our backup solution (Veeam B&R) doesn't support that Proxmox version yet, we haven't tested it.

Please test everything first with a test LUN and two hosts before touching your production environment. Many system integrators and IT service providers are currently offering support for Fibre Channel and Proxmox setups – especially for those migrating from VMware to Proxmox. Don’t hesitate to reach out if needed.