External CO2 extinguishers certainly help. But requires the alertness of a trained personnel to use the same effectively during a fire.
I have also come across a solution wherein the extinguisher is kept always connected to continuously deliver pressurized gas such as CO2, FM-200, etc. through a heat sensitive tubing which is routed from within your equipment, in such a way that the tubing ruptures during increase in ambient heat (as is caused during a fire) and allows this "gas" to engulf the concerned area and thereby starve the fire.
Technically, it is similar to a "First Aid" rendered during an accident. This does not replace the action of external fire fighters but reduces the severity during an occurance.