For WDL questions, see the WDL specification and WDL docs.
For Cromwell questions, see the Cromwell docs and please post any issues on Github.
If I understand correctly, call-caching works by copying the files from a previous workflow provided that the script, input are the exact same. But since WDL is copying file it is taking up too much disk space. Is there a way to make it do hard or soft linking instead?