Locally I can call mongod --noprealloc --nojournal to prevent preallocation. I want to configure my mongo database on Appfog the same way. I tried using af tunnel to access the database instance, however it only provides the options
1: none
2: mongorestore
3: mongodump
4: mongo
I also thought of configuring the Appfog mongo database when I connect to it on my Nodejs server, using mongodb node native. Unfortunately this has not given me any luck either.
I never found a way to do this using mongodb on Appfog. My intent for doing this was to prevent the mongodb running over the 100mb Appfog storage limit. I instead moved my database to MongoLab which is supported by Appfog. They somehow seem to save data differently, so that it takes up very little space compared to saving it on Appfog.