[John McClary] “Sounds a little crazy but is it even theoretically possible?”
Not sure there’s a way to mount specific clients as read-only. I fooled around with it once just using OSX permissions like you suggested. Results were weird. I’d copy a folder to the disk using one client, and the other client couldn’t see the files. Even after I disconnected and reconnected. Even if it worked, I think every time you remount it the permissions for the client get reset to RW. And I think even mounting it with multiple clients can cause filesystem corruption.
If you want a crazy idea, the one I had was to run an OpenSolaris box and set up it’s iSCSI server. OpenSolaris uses the ZFS filesystem (which is the best filesystem there is – it’s better than using hardware RAID-5). OSX Leopard can read ZFS, but not write to it. So I wondered what would happen if you connected a bunch of different Mac iSCSI of FC clients to it. It would at least be safe since the Macs cannot have write access at all.
And since it’s ZFS, not HFS+, the server box would have local access to it and you could give it a mount point, enable SMB service, and access it via regular filesharing for all your write access needs. Does anyone really even need block-level write access?
Anyway, just a thought. If you’re serious though you should consider buying MetaSAN. Aside from preventing data corruption, it has disk caching and other things that make a SAN functional.
Sean