Does a journaling file system only keep a log/metadata about data written to disk or does it do more than that? Can an erased file be reconstructed from the data kept by the journaling file system? i'm thinking not because that would mean an exact copy of data is being kept and that doesn't make sense because id be running out of disk space twice as quick... i'm confused about how this works, please assist... thanks

I'm using vista an xp.