What is the LAN storage? Make, Model?
Generally there would be two approaches, the first is to have the Mac login to it using typically NFS and then it is able to 'reshare' it using e.g. AFP to other Macs. It could of course simply use it itself however it sounds like at least if you connect via AFP it will not consider it suitable for use to store things like the mail server data (this might work if you use NFS).
The otherway - the 'SAN' way, would be to use an iSCSI initiator on the Mac to connect to the device however this is only possible if the device supports acting as an iSCSI server (low end NAS boxes typically do not). You would also need to buy an iSCSI initiator for the Mac (the client) as this is not built-in, there are two choices -
I don't know about the second one but the first is compatible with Apple's XSan software meaning you could then share the iSCSI target (the server) between multiple Macs simulataneously.
I would expect if you use iSCSI that it could then be used with other server functions on the Mac.
Your device is a NAS, it is allready a fileserver itself. No need to file share it to the Mac-server and then fileshare it again. Will onlu give you lots of problems.
If you like to share it using the Mac you have to connect it directly, Firewrire, USB3, Thunderbolt etc.
Usually a NAS is a NAS and they can't act as a basic storage device.
@John Lockwood: Thanks for your clear clarification of how this might be set up.
@jhellstrom: Thank you for pointing out what was before not at all obvious to me. Seriously.
My original plan was to set these drive up in a NAS/SAN environment thinking that having it on my home LAN would make it available for others in my household to access via Ethernet. Secondarily I wanted to move a very small (low bandwidth) website from a remote host service to this LAN setup, again thinking that would be more out of the way and not intrusive to my normal working/playing on my Mac.
So with what you've both stated, it appears that the best way is to hook these drives up as local external volumes via FW. I'll just go back to step 1 and see what happens.
Very few NAS boxes would allow connecting them directly to a Mac via FireWire, in fact there is only one which is a few Drobo models. A few more might support using USB.
Some people want to use a NAS as server storage (using the NFS or iSCSI methods I mentioned) to then use that storage for things like Network login home directories.
What would a website have to do with the NAS box? The nearest I can think of to this is that some NAS boxes can themselves act as the web-server, this would not need you to connect it directly to a Mac. You could with for example a ReadyNAS Pro, use it both as a web-server, and as a file server, and also link a Mac server to the NAS (via NFS or iSCSI). The ReadyNAS cannot be connected to a Mac via FireWire or USB though.