I have a large geotiff file (dem) that I am planning to use with r.watershed to delineate a very large drainage basin. The file is 142 GB. When I try to run r.watershed after a few second it gives me error messages (ex: unable to write ...). I tried a different approach by clipping a small portion of the geotiff and run r.watershed again. This time r.watershed runs properly, and all the support output files are created. My question, is there a way to process a large geotiff in r.watershed?
When reading the documentation at https://grass.osgeo.org/grass73/manuals/r.watershed.html
It says you should use the -m flag so that the process is not run in memory. This will make the processing slower, but it should work if you have sufficient disk space.