If the OS is 64 bit and you have enabled the large file option at the OS level, then it's ok to have a large dbf. Else it is recommended that it not be more than 2047M. My OS is 32 bit w/o the large file option and I do not let the size of any file exceed 1995M. With a 64 bit OS and large file option, you can have a file as large as 1 terabyte.