International Business Machines Corporation

Paul Jonathan Quelch

Gordon Douglas Hutchison

Robert Bruce Nicholson

Ian David Judd

Henry Esmond Butterworth

Paul Nicholas Cashman

Reginald Beer

Robert Frank Maddock

Paul Hooton

Neil Morris

Barry Douglas White

William James Scales

Steven John Hyatt

Stephen Arthur Randle

Steve John Hyatt

Following a loss of power, a storage system switches to a local power supply. The system switches to the local power supply, prevents the receipt of input/output commands and copies the content of cache memory to a local storage device. On detecting resumption of external power, the system charges a local power supply, copies the content of the local storage device to the cache memory and processes the content of the cache memory with respect to at least one storage volume. When the charge stored on the local power supply exceeds the charge required to copy the content of the cache memory to the local storage device by a predetermined amount, the system allows the receipt of input/output commands using a reduced portion of the cache memory. Once the charge stored on the local power supply has reached a predetermined level, the system allows the receipt of input/output commands using all cache memory.

Method for resuming a system from a power failure after the main power supply has recovered and prior to fully recharging the backup power supply by enabling the reception of input/output commands by the cache memory at a rate proportational to the amount of charge on the backup power supply currently available

Apparatus for resuming a system from a power failure after the main power supply has recovered and prior to fully recharging the backup power supply by enabling the receiption of input/output commands by the cache memory at a rate proportational to the amount of charge on the backup power supply currently available

A method of operating a storage system comprises detecting a cut in an external power supply, switching to a local power supply, preventing receipt of input/output commands, copying content of cache memory to a local storage device and marking the content of the cache memory that has been copied to the local storage device. When a resumption of the external power supply is detected, the method continues by charging the local power supply, copying the content of the local storage device to the cache memory, processing the content of the cache memory with respect to at least one storage volume and receiving input/output commands. When detecting a second cut in the external power supply, the system switches to the local power supply, prevents receipt of input/output commands, and copies to the local storage device only the content of the cache memory that is not marked as present.

Recycling of cache content

According to one general embodiment of the present invention, there is provided a computer program product for reducing incidence of errors in connections between a power consumer apparatus operable to draw a load and a power supply apparatus capable of varying the power supplied, the computer program product comprising: a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising: computer readable program code configured to generate at the power consumer apparatus an identifiable pattern in a load to be drawn from a power supply connection to a power supply apparatus; and computer readable program code configured to monitor at the power consumer apparatus for a change in the load corresponding to the pattern, the monitoring being performed across a signal connection to the power supply apparatus; wherein a positive result of the monitoring indicates a correct configuration. Additional embodiments are also presented.

Connection error avoidance for apparatus connected to a power supply

A replicated state machine includes multiple state machine replicas. In response to a request from a client, the state machine replicas can execute a service for the request in parallel. Each of the state machine replicas is provided with a request manager instance. The request manager instance includes a distributed consensus means and a selection means. The distributed consensus means commits a stimulus sequence of requests to be processed by each of the state machine replicas. The selection means selects requests to be committed to the stimulus sequence. The selection is based on an estimated service time of the request from the client. The estimated service time of the request from the client is based on a history of service times from the client provided by a feedback from the state machine replicas. As such, requests from multiple clients are serviced fairly.

Replicated state machine

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 system, method and computer program for configuring power supply apparatus to supply a voltage optimized to tolerate a range about a nominal operating voltage of a device comprises a tester to test and communicate to a comparator a present utility voltage value. The comparator compares the present utility voltage with a present nominal operating voltage of the device. A configurator responds to the present utility voltage falling within an upper half of a first range having a centre point higher than the present nominal operating voltage and lower than an upper out-of-tolerance voltage of the device or within a lower half of a second range having a centre point lower than the present nominal operating voltage and higher than a lower out-of-tolerance voltage of the device, by configuring the power supply apparatus to supply a voltage respectively within the first range or the second range.

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Emsworth, United Kingdom

Paul Jonathan Quelch