If you are on Unix, I'd say just test it if you have a local filesystem that you don't mind if it gets full and it supports large files (i.e. > 2GB in size). Most unix filesystems will create a "sparse" (aka holey) file, without actually allocating all of the space. Just create a file, seek way the heck out there, and write one byte. It should only really be one disk block long, but appear in a directory listing as huge. I think this is true for NFS as well, but it may depend on the implementation.