Can someone explain the important differences between fabric, point to point, and loop on a fibre san?

Solution 1:

If you have a single port on each switch that's logging in as a loop port, you need to address this. The first thing I'd do is try unplugging it and plugging it back in. If it still shows up as a loop port when it relogs back into the fabric, take a look at hard-coding the port to be an F port. I found instructions here.

Be prepared that if there's some underlying problem that is causing it to default to loop ports, this might prevent the port from coming online. If that happens, you'll need to open a support call and possibly replace hardware.

The reason you need to address it is mostly because it's a sign of something else possibly wrong. The part of the FC address space they use is now used by NPIV, however that's not something typically needed by an HP MSA storage device. If it's working well enough that you don't want to take risks, you can leave it. That said, it is best practice to not use FL ports unless you have no other choice.