NAS and managing electrical mains

[Francesco Antonetti Lamorgese Passeri]

Hi,

I've Kubuntu 11.10 on my notebook and a Lacie NAS wired to my home LAN. 
Usually i mount the shares on the NAS as local file systems (/mnt/NAS), 
to make it usable for certain software not supporting network protocols. 
I would solve this problem: sometimes happens the elctrical mains goes 
down suddenly, so my notebook loses the connection to the NAS. In this 
case, if i turn off the notebook, it takes several minutes to shutdown, 
beacuse, i suppose, the system don't recognizes the connection loss. How 
can i instruct the system to recognize the connection loss quickly and 
unmount the remote partitions?

Thank you very much

Francesco