Patent Application
20050132022
The present invention relates generally to computer systems, and specifically to systems in which computers are linked to peripheral devices via a packet network.
Nearly all current computer systems, from desktop personal computers through high-end servers, include multiple input/output (I/O) connections to peripheral devices. A typical computer has I/O connections for a video display, keyboard, mouse, floppy disk, USB ports, hard disks (SCSI and/or IDE), serial port, parallel port, audio, and local area network (LAN) interface. Each peripheral device is controlled by a specialized hardware controller, which on one side connects to the peripheral device, and on the other side connects to the rest of the computer system via one of several buses. The buses may be proprietary or standardized, such as the standard PCI, PCI-X, and AGP buses. These buses are typically connected to the central processing unit (CPU) through either one or two system controller chips, commonly referred to as the “North Bridge” and the “South Bridge.”
A number of new standards have recently been promulgated to permit accessing at least some I/O peripherals remotely, via packet networks. For example, the iSCSI protocol provides remote, SCSI-like disk access over Internet Protocol (IP) networks. As another example, the InfiniBand™ architecture permits computing hosts and peripheral to be linked by a switching network, commonly referred to as a switching fabric. The InfiniBand architecture is described in an article published by the InfiniBand® Trade Association (www.infinibandta.org/ibta/, 2003), entitled “An InfiniBand Technology Overview.” As noted in this article, InfiniBand provides a mechanism to remove I/O from the server chassis, so that I/O interconnects may be shared among many servers. This approach is said to permit design innovations such as dense server blade implementations.
In embodiments of the present invention, a computer comprises a CPU and a LAN interface, along with local memory and a system controller for interfacing among these elements. Typically, the computer comprises no other on-board buses or I/O controllers, except for the LAN interface and the bus that is used to connect it to the system controller. All I/O traffic between the computer and peripheral devices is carried in data frames, for example, Ethernet frames containing IP packets, over a LAN to which the LAN interface is connected. The LAN interface thus performs dual functions, providing the computer with access to both network communications and I/O functions.
Eliminating specialized I/O controllers and buses from the computer conserves substantial board space and power, as well as reducing the complexity, cost and management effort that must be invested in the computer and increasing its MTBF. These enhancements are particularly meaningful, for example, in a server blade or cluster environment, in which much of the generic I/O functionality (other than disk access) is rarely needed. Multiple servers of this sort may be connected to the LAN in order to share I/O resources via their respective LAN interfaces. A user console may be connected to the LAN in order to permit a user, when required, to enter keyboard or mouse inputs to each of the servers via the LAN, and to view the video output therefrom as required, likewise via the LAN.
There is therefore provided, in accordance with an embodiment of the present invention, a computer system, including:
Typically, the computers and the console are arranged to communicate over the LAN by transmitting Layer 2 data frames. In one embodiment, the computers and the console are arranged to convey the input and the output by tunneling over Layer 2 on the LAN. In another embodiment, the computers and the console are arranged to encapsulate the input and output in Internet Protocol (IP) packets for transmission over the LAN. In an alternative embodiment, the computers and the console are arranged to encapsulate the input and output using an application-layer protocol.
In a disclosed embodiment, the system includes an input/output (I/O) device, coupled to the LAN, wherein the computers are arranged to transmit I/O commands over the LAN to the I/O device and include no on-board I/O device controllers. Typically, each of the computers includes an emulation processor, which is coupled to trap the I/O commands from the at least one CPU while emulating the I/O device, and to encapsulate the I/O commands in data frames for transmission over the LAN to the I/O device, so as to cause the I/O device to fulfill the commands.
There is also provided, in accordance with an embodiment of the present invention, computer apparatus, including:
In a disclosed embodiment, the apparatus includes substantially no on-board device controllers other than the network interface and the emulation processor.
There is additionally provided, in accordance with an embodiment of the present invention, an emulation device, including:
There is further provided, in accordance with an embodiment of the present invention, a method for computing, including:
There is moreover provided, in accordance with an embodiment of the present invention, a computer system, including:
There is furthermore provided, in accordance with an embodiment of the present invention, a method for computing, including:
The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which:
Computers 22 use LAN 24 both for conventional network communications—with other computers in system 20 and with computers outside the system—and for I/O functions. In the present example, computers 22 may access storage devices 26, such as a hard disk or disk array, via LAN 24. Typically, the computers comprise no local storage. Other peripheral devices, such as a printer 27, may likewise be connected for remote access via the LAN. In an exemplary embodiment, computers 22 communicate over LAN 24 by transmitting and receiving IP packets, and suitable IP-based protocols are provided for accessing the peripheral devices. For example, the computers may access storage device 26 using the iSCSI protocol. As another example, computers 22 may access peripheral devices using application-level protocols, as are known in the art, such as the Hypertext Transfer Protocol (HTTP) or Virtual Network Computing (VNC). Alternatively or additionally, computers 22 may communicate with peripheral devices by transmitting and receiving Layer 2 data frames, such as Ethernet frames, over LAN 24. In this case, suitable tunneling protocols may be used to encapsulate storage commands and data, and similarly other I/O signals, in the Layer 2 frames.
A console 28 permits the system operator or other user to access each of computers 22. Note that computers 22 have no on-board user interface devices, such as a video adapter, keyboard adapter or serial port. Rather, a keyboard 30, mouse 32 and video monitor 34 are provided as part of console 28. Keyboard and mouse inputs by the user of console 28 are encapsulated in IP packets or Layer 2 data frames for transmission over LAN 24 to the selected computer 22. Video signals generated by the computer are similarly encapsulated and transmitted to console 28 for display on monitor 34. If computer 22 is running a Unix® or Linux®-type operating system, the X-Windows protocol may be used for communication between the computer and console 28. Alternatively, for operating systems such as Microsoft Windows®, computer 22 and console 28 may be provided with video drivers that encapsulate and de-encapsulate Windows Graphic Device Interface (GDI) commands in IP packets.
Each computer 22 comprises one or more CPUs 36, which are coupled by a system controller 38 to one or more LAN interfaces 40. Details of an exemplary system controller and LAN interface circuits are shown in
Computer 22 may perform the network-based boot and I/O access functions described herein under the control of software, which is typically stored in non-volatile memory 46 and/or on storage device 26. This software may be provided in electronic form, by download over network 24, for example, or it may alternatively be supplied on tangible media, such as CD-ROM or non-volatile memory.
For convenience of implementation, computer 50 comprises a number of legacy components, which are used in existing, bus-based server blades. For example, CPUs 36 may be Xeon processors, made by Intel Corp. (Santa Clara, Calif.), while system controller 38 is an off-shelf North Bridge device, such as a LE-type chip produced by the ServerWorks division of Broadcom Corp. (Irvine, Calif.). This system controller chip comprises a memory controller 58, for interfacing with local memory 42, as well as CPU interface ports 62 for coupling to CPUs 36, and peripheral interface ports 64. The elements of controller 38 are linked together by an internal bus 60. It will be understood that the specific components mentioned here and the internal structure and arrangement of these components are described here only by way of example. Alternative realizations of the principles of the present invention will be apparent to those skilled in the art.
One of ports 64 of controller 38 is connected to a fast Ethernet interface 68, such as a Broadcom BMC5703S Gigabit Ethernet controller. (If desired, a bus bridge, not shown in the figures, may be used to connect port 64 to multiple parallel Ethernet interfaces.) Ethernet interface 68 connects to LAN 24. In the server blade environment, the LAN connection is typically made via a backplane connector to LAN wiring in a backplane of the server rack (not shown) in which computer 50 is mounted.
In order to make these legacy components work in the novel, LAN-based I/O architecture of the present invention, computer 50 comprises a novel “legacy emulation” (LEM) device 52 (which may also be referred to as an emulation processor), which interfaces between system controller 38 and LAN 24. Device 52 typically comprises a semi-custom or field-programmable chip, such as an ASIC or FPGA chip. Although device 52 is shown, for the sake of clarity of explanation, as comprising a number of different functional blocks, all these functions may be performed by a single chip. Alternatively or additionally, device 52 may comprise two or more separate chips, or a single custom chip.
LEM device 52 comprises I/O trap logic 70, which is connected to one of peripheral interface ports 64 of controller 38. Logic 70 intercepts outputs sent by CPUs 36 to peripheral devices, including:
To communicate with peripheral devices, service processor 72 typically establishes TCP/IP connections over LAN 24 with the controllers of the peripheral devices. Service processor 72 transmits the TCP/IP packets via a dedicated Ethernet interface 74 to LAN 24. Alternatively, the service processor may use the existing Ethernet interface 68 to transmit and receive packets over the LAN if the interface is not required for other communication traffic. As a further alternative, Ethernet interface 74 may be connected to the LAN via a hub (not shown), to which interface 68 is also connected.
Similarly, service processor 72 receives packets over TCP/IP connections containing inputs from peripheral devices, such as keyboard 30, mouse 32 and other data inputs. The service processor de-encapsulates the inputs and conveys them to logic 70, which then passes the inputs via controller 38 to CPU 36. As noted above, logic 70 virtualizes and emulates the behavior of conventional, standard I/O devices. Computer 50 may thus run a standard operating system, such as Windows®, substantially without modification. CPU 36 and controller 38 need not be aware that they are dealing with remote peripherals via LAN 24, rather than local peripherals connected by conventional I/O buses.
Service processor 72 also interfaces with non-volatile memory 46, in order to initiate the boot sequence of computer 50 upon power-up or reset. Real-time clock 44 is omitted from
Where network-based I/O protocols are available, computer 50 may be programmed to use these protocols, rather than I/O emulation via LEM device 52. For example, the computer may be programmed to access disks using the iSCSI protocol via one of Ethernet interfaces 68. Similarly, as noted above, network boot and X-Windows may be used for remote boot and console interface functions when computer 50 is running an operating system that is compatible with these protocols.
Comparing computer 50 to server blades known in the art, it will be observed that computer 50 has a substantially smaller chip count: no South Bridge, and no interface or controller chips for keyboard, mouse, video, audio, USB, serial and parallel ports or disks. Therefore, computer 50 consumes less power, is less costly to produce, and can be packed more densely into server racks than can server blades known in the art. Although
It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.
