System Storage Taking a Huge Hit!

[Michael25967188dyl9]

So i'm working on a map... the base map layer I'm using is about 140GB (very high res) then I've placed about 400 markers on the map in the form of PNG's (about 4MB each). When I save the PSD it ends up about 2.5GB... The problem I'm running into is this...

I'm trying to create a border round the map, equal spacing Top Right and Left with a larger gap at the bottom to write some text. Whenever I move the map and its markers into position and open up the break down of storage usage on my Mac, the space being used for system storage goes from about 100GB to about 207GB. At this point I can't save the file because there isn't enough Scratch Disk space. Is this a bug? Am I doing something stupid? Is it simply because the files are so big and PS has to save instances if i want to undo an action for example... how can I solve this?

[D Fosse]

This is normal and expected. 

The scratch file contains all history states for all open documents, plus overhead for advanced functions like smart objects etc. Each history state can potentially add the full uncompressed file size.

Raster image editing moves huge amounts of data. With Photoshop, there is no such thing as "enough RAM". Total memory requirement is usually much higher. Hence the scratch disk. You should normally have around 200 GB to 500 GB free space, depending.