folder structure for storing information about IT within a company

I’ve read countless IT Management books but nothing seems to guide you on some of the really simple stuff that we all must do.

For example what filing structure do you use within your department ? Do you file functionally or geographically first ?

eg

hardware
=> routers
=> brisbane
=> perth

is a router a piece of hardware or is it “networks”. and so the decision points go on and on

would just be interested to see what structure everyone else uses..