More than a Mouthful
I want to work with an area but JOSM won't download it. What are my options?
Downloads of larger areas, like all of metropolitan London, causes a large burden on the OSM server. We've limited the area that the server will download at one time.
Option One: smaller bites
You can break your download into a few smaller, bite-sized chunks to get the area you want.
Option Two: planet file
The planet file is a snap shot of the OSM data taken once a week. You can download the entire planet and reduce load on the server. Gagravarr described this on the mailing list.
The trivial workaround is to grab the latest planet, then use any one of the number of scripts that will excerpt part of the planet without the need of a database. If it's just a simple lat,long bounding box, then sling it through
If it's a fancy geometry, use
(possibly having added your own area first)