> 
> I'm proposing this to be a [canonical question](http://meta.serverfault.com/questions/1986/what-are-the-canonical-answers-weve-discovered-over-the-years) about enterprise-level Storage Area Networks.
> 
> 
> 

What is a Storage Area Network (SAN), and how does it work?  

How is it different from a Network Attached Storage (NAS)?  

What are the use cases compared to direct-attached storage (DAS)?  

In which way is it better or worse?  

Why is it so expensive?  

Should I (or my company) use one?