using josm for big aera

Hello and thanks for this software and this forum

I 'm french, 43 and want to use JOSM for exporting streets and road of a huge “Region of Paris” in order to do our simulator mod map in Digital Combat simulator

1st we tryed to download it directly and i have this message :

so someone told me to do this:

Try to do next steps:
1. Download and install latest stable version of JOSM (14289):
2. Open JOSM -> "Edit" -> "Preferences" (F12)
3. "Overpass Server" -> on "Use Overpass Server..." checkbox -> on "Expert Mode" checkbox -> "OK":
4. "Download" -> "Download from Overpass API" -> choose boundaries of your own region -> "Download":

i ve done but always this problem (you can see the size of the map)

Is it a bug of JOSM or what is the maximum size of data ? does someone have a clue to do this job ?

Thanks a lot

The area is too big to download all data within. If you need only the streets try highway=* in the overpass turbo wizard

Thanks for the clue ! if i need water or other layer what are all the command possible ?

There are no such layers in osm. You must filter by object type (node, way, relation) and their tags.
Most water related features are in natural=water and waterway=*, but there are some other tags too.