DCS CW map has a size of 890km x 900km = 801.000 km², requiring 205GB SSD space. Whole Europe (excl. Greenland, incl. Russia west of Ural) is about 10,5 mio km². that's approx. 13x the size. I assume lesser populated areas with less airports, cities etc. should also require less memory size. Phase IV++ map might fit on a 2TB SSD and will definetly fit on a 4TB SSD.
Just to plan your next SSD purchase