See this thread for more details. The large file that gets uploaded is called charmm.out and is basically the log file that the application uses to write information to. Normally, when the application exits without error, this file only contains the string \'NO ERRORS\', but in the case of an error, we would like to have this file back on the server so that we can better find out why our application was not doing what it was supposed to do. We realize this file can grow very large and we have enabled this feature only for this test phase where we need as much information as possible to solve the problems we find with our app. Later on, this uploading will be disabled or we will only send back the minimum amount of info. One of the main reasons that charmm.out can grow really large is if your machine crashes or freezes when the application is in the middle of writing checkpoint data to disk. After BOINC restarts the application, it will crash, because it finds incomplete data in the file percentdone.str. This can even occur at 80 or 90% of crunching time. We are looking at how to make checkpointing a more atomic operation so that this will not happen as much anymore.