International Business Machines Corporation

Paul Hooton

Robert Bruce Nicholson

Paul Nicholas Cashman

Reginald Beer

Robert Frank Maddock

Ian David Judd

Neil Morris

Barry Douglas Whyte

Paul Jonathan Quelch

Barry Douglas White

An apparatus, method, and computer program for maintaining access times in a data processing system, wherein the data processing system comprises a plurality of storage devices, the apparatus including: a receive component, for receiving a command or an availability message, wherein an availability message indicates whether the storage device is available; an evaluate component for evaluating a plurality of first relationships between the storage devices and a plurality of first values, wherein each of the first values indicates whether a related storage device is a redundant; a send component, for sending a power message to one or more of the storage devices; and an update component for updating a second relationship between the redundant storage device and a plurality of second values, wherein each of the second values indicates whether a related redundant storage device is available.

Maintaining access times in storage systems employing power saving techniques

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 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 ().

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Eastleigh, United Kingdom

Paul Hooton