you can create RAM disk or temporary file system using the following command
mount -t tmpfs -o size=32M tmpfs /var/lib/asterisk/
the above command will mount /var/lib/asterisk/ directory in the RAM and its size will be 32Mb.
you normally use RAM disk for the applications that require intensive io operation. using ram disk will increase hardisk life and also increase performance of application by reducing access time.
mount -t tmpfs -o size=32M tmpfs /var/lib/asterisk/
the above command will mount /var/lib/asterisk/ directory in the RAM and its size will be 32Mb.
you normally use RAM disk for the applications that require intensive io operation. using ram disk will increase hardisk life and also increase performance of application by reducing access time.