Disk system adapted to be directly attached
A network-attached disk (NAD) system is disclosed that includes an NAD device for receiving a disk access command from a host through a network, and a device driver at the host for controlling the NAD device through the network, where the device driver creates a virtual host bus adapter so that the host recognizes the NAD device as if it is a local device to the host. The host may run the UNIX or Windows family of operating systems. The NAD device includes a disk for storing data, a disk controller for controlling the disk, and a network adapter for receiving a disk access command from the host through a network port.
1. A method of accessing a network coupled device through a network carrying general-purpose network traffic using a certain network protocol from a host having an internal host system bus and running an operating system, the method comprising:
operating a virtual host bus adapter at a device driver level for controlling the device through the network via a network interface, the virtual host bus adapter including a device driver enumerating devices that are available over the network, not directly attached to the host internal system bus, so that the host recognizes the device as a host local device, the virtual host bus adapter controlling the device in a way indistinguishable from the way it is controlled as a physical host bus adapter device controlling the same type of device so that the host recognizes the device as if it is a local device connected directly to the system bus of the host;
encapsulating device level commands and optional data for controlling the device into outgoing data link frames for communication over the network;
communicating the outgoing data link frames on the network;
receiving the outgoing data link frames and extracting the device level commands and optional data;
communicating the extracted device level commands and optional data to the device and operating the device in accordance with the extracted device level commands;
generating an incoming command and optional data and encapsulating it into an incoming data link frame for communicating to the host over the network;
sending the incoming data link frame to the host; and
extracting the device level command and optional data from the host received data link frame and processing the device level command in accordance with predetermined rules.
2. The method of claim 1 , wherein the device level commands contained in and extracted from the data link frames are the same device level commands that are used to access the same type of device when such same type of device is connected to the host over the internal host system bus.
3. The method of claim 1 , wherein the operating system is a member of the UNIX family of operating systems.
4. The method of claim 1 , wherein the operating system is a member of the Windows family of operating systems.
5. The method of claim 4 , wherein the virtual host adapter is configured to operate according to the Network Driver Interface Specification.
6. The method of claim 1 , wherein data link frames are compatible with TCP/IP.
7. The method of claim 1 , wherein the network coupled device is a disk.
8. The method of claim 1 , wherein the network coupled device is a tape device.
9. The method of claim 1 , wherein the network coupled device is a compact disk drive.
10. The method of claim 1 , wherein the network coupled device is a digital versatile disk device.
11. The method of claim 1 , wherein the network coupled device is a memory device.