Storage servers use a fast, non-volatile or persistent memory to store data until it can be written to slower mass storage devices such as disk drives. In the multicast transmission system for performing multicast transmission to a plurality of terminal stations from a base station, when an error is detected in the terminal station, the terminal station utilizes some of sub-carriers constituting an OFDM symbol to generate and transmit a NAK signal to the base station. One or more elements of the displayed program code can be linked to a data file having one or more implementation instructions for elements of the computer program. Component connection points for an electrical component are included on the outer frame. The NAS and SAN controllers are capable of operating independently of each other.