International Business Machines Corporation

Reginald Beer

Ian David Judd

Robert Frank Maddock

Robert Bruce Nicholson

Paul Nicholas Cashman

Paul Hooton

Neil Morris

Barry Douglas Whyte

Paul Jonathan Quelch

Peter John Deacon

Barry Douglas White

Stanley J Cutts

Vinay V Shah

Michael Alan Veal

David Newmarch

Steven Brian Kew

Hamish Birrell Williamson Halley

A method and apparatus for relating a device name to a physical location of a device () on a network is provided. The network may be a serial loop network, for example a Fibre Channel Arbitrated Loop network. The network includes a plurality of devices () on or connected to the network () and a control device () with control over at least one of the devices (). Each device () has a check output () independent of the network () with connection means () to a control device (). The method includes the step of sending a device name from the check output () of a device () to the control device (). The check output () of a device () is also connected to an external indication means for indicating the failure of the device ().

Method and apparatus for relating device name to physical location of device on a network

A logic arrangement, method and computer program for reducing incidence of errors in a redundant path system during a process of attachment of a device to a running subsystem, comprises a control component for encapsulating the process of attachment of a device to a running subsystem; a disabling component for disabling a path interface; a testing component for testing for the presence of a usable data path across at least one further path interface; and an enabling component for enabling the at least one further path interface to accept communication with the device responsive to a positive outcome from the testing component; wherein the control component is adapted to permit operation after attachment of the device only if full redundancy is retained. A re-enabling component may re-enable any path interface or further path interface.

Method and apparatus for improved error avoidance in a redundant data path system

A method and apparatus for recovery from faults in a loop network () is provided. The loop network () has a plurality of ports () serially connected with means for bypassing the ports () from the loop network (). A control device () is provided with bypass control over at least one of the ports (). A host means () sends a command to the control device () at regular intervals and the control device () has a counter which restarts a time period at the receipt of each command. If the time period expires, the control device () activates the means for bypassing all the ports () under its control. The loop network () may have two loops () with at least some of the ports () common to both loops ().

Method and apparatus for recovery from faults in a loop network

A method and apparatus for detection of a port name in a loop network is provided, particularly a loop network in the form of a Fibre Channel Arbitrated Loop (FC-AL). The loop network () has a plurality of devices () each device () having at least one port () on the loop network (). The method includes determining which ports () are populated with devices () for which the unique port name (WWPN) is not known. The populated ports are then all bypassed and a mode is entered on the loop network () in which idle frames are transmitted around the loop network (). One port is un-bypassed at a time and the port name from the un-bypassed port is received and recorded. The port name is received from the un-bypassed port in a Loop Initialisation Select Master (LISM) frame transmitted by the un-bypassed port.

Method and apparatus for detection of port name in a loop network

A method and apparatus for recovery from faults in a loop network () is provided. The loop network () has a host means (), a first loop and a second loop (), a plurality of ports () connected to each of the loops () and a control device () on or connected to each loop () with bypass control over at least one of the ports () connected to the loop (). In the event of a failure on the first loop (), the host means () instructs the bypassing of at least one port () on the first loop (), the host means () sending the instructions via the control device () on or connected to the second loop (). The host means () may determine the physical topology of the ports () on the first and second loops () such that when a failure is reported to the host means () by a port () on the first loop (), the host means () instructs the bypassing of a port () in a specific relationship to the reporting port () on the first loop (). The host means () may instruct the bypassing of all ports () on the first loop () and subsequently selectively un-bypass ports () to ascertain the location of a faulty port or ports.

A method and apparatus are provided for fault location in a loop network (). The network system having a host port () for supplying and receiving data and a plurality of successively connected ports () through which data from the host port () is transferred. A counter () for each port records data transfers in which the amount of data received at a destination port is less than an expected amount of data. When a transfer with less than the expected amount of data is identified for a data flow between a sending port () and a destination port (), the counters are incremented for each port () after the sending port up to and including the destination port. Analysing means determines a fault location in the network system from the distribution of counts in the counters ().

Method and apparatus for fault location in a loop network

A method is provided for remotely controlling power to electronic devices. Each device includes two or more ports for receiving signals over the serial link. The method includes issuing a shutdown command from the host data processing system to selected one of the devices over the link and responsive to the receipt of a power-off command at a device, causing the device to enter a low power standby mode on cessation of signal activity at one of the device ports. On entering standby mode at a device, standby power is supplied in the device to allow the device to monitor the one or more device ports for incoming signals. In addition, transmission of signals via the one or more ports is ceased. On receipt of a signal at any of the one or more ports that was previously inactive, power is restored to the device.

Remote power control

A data processing system comprises a host computer connected for the transfer of data to and from a plurality of data storage devices arranged in a string, the host computer including communication means comprising first and second ports connecting to first and second communication links, the first and second communication links being connected respectively to first and second data storage devices of said string. A bypassing means is provided between the first and second ports of the host system and the first and second data storage devices, the bypassing means being comprised of an independent bypass circuit on each of the first and second communication links between each of the first and second ports and the first and second data storage devices, the bypassing means being operable to bypass the host computer by connecting the first and second devices only when both of said independent bypass circuits detect a lack of data transfer on their respective links.

Bypass circuit for bypassing host computer which are connected to

An error recovery method for use in an information communication system which comprises a plurality of nodes connected by links. Information is transferred between the nodes in frames of predefined types, including at least a first frame type used to transfer data and a second frame type used for error recovery. Each node has at least a first and a second mode of operation. In the first mode frames of both first and second types are accepted. In the second mode frames of the first type are discarded and only frames of the second type are accepted. A master node which controls error recovery is selected from amongst those nodes which can initiate transfers.

Multiple node dual level error recovery system and method

Optimized method of data communication and system employing same

A cooling system provides redundant fault-tolerant cooling to electrical devices in an electrical apparatus and comprises a plurality N+1 individual cooling fans, N cooling fans being required to provide cooling of the devices and further comprises monitor logic for monitoring the status of the plurality of cooling fans and for issuing a non-critical warning to the apparatus in the event of failure of one of the cooling fans, the logic being further operable, in the event of a failure in the logic, to issue a non-critical warning to the apparatus.

Fault tolerant cooling in electrical apparatus

Described is a network addressing scheme in which a message sent from a source node to a destination node includes a path address which defines the path over which the message should travel to reach the destination node. At each node along the path between the source and destination, the path address is compared against a predetermined value, and on determining that the address and predetermined value are different, the node modifies the address before forwarding the message onto the next node. In a switch node having three or more ports, the identity of the output port is determined from the path address and a portion of the address is deleted before sending the message out on that output port. Also described is a method of configuring a network in which one or more initiator nodes are defined, the initiator nodes issuing query messages to an adjacent node which responds by sending the initiator details of the number of operational ports which are implemented in the adjacent node. The initiator node then issues query messages addressed to those nodes which are attached to the operational ports on the adjacent node. This continues until the initiator has walked through the entire network at which point the configuration process is complete.

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Eastleigh, United Kingdom

Reginald Beer