International Business Machines Corporation

Thomas W Rickard

William James Scales

Carlos Francisco Fuente

Matthew John Fairhurst

David Adam Sinclair

David C Conway-Jones

Peter M Smith

Alistair Laesk Symon

David J Brown

This invention relates to a method, system and computer program product for reading data from a storage controller in storage area network. A read data instruction is received from an application requesting data from the storage controller using a primary data path. If the data on the primary data path is not transferred in a defined time interval using the primary data path, data is requested from the storage controller using one or more alternative data paths. Data is received from the storage controller on one of data paths and into a buffer. When the read instruction has completed and that the data is in the buffer, the application is notified. Each data path is associated with a buffer and the data is received into a buffer associated with the path. The application is informed which buffer holds the data and the application accesses the data from this buffer.

Method, system, and computer program product for reading data from a storage controller in a storage area network

An apparatus operable with a host and a data storage component for detecting a storage device susceptible to failure under I/O workload is provided. The apparatus includes a selector component for selecting a pair of storage devices in the data storage component. A data migration control component is provided for initiating migration of data from a first to a second storage device of the pair of storage devices. An I/O workload mirroring component is provided for mirroring an I/O workload from a first of the pair of storage devices to a second of the pair of storage devices. A storage device failure detecting component for detecting failure of one of the pair of storage devices is also included. The selector component further comprises a timer component for periodically initiating the selecting.

Early detection of storage device degradation

A host data processing system includes a data storage system having a cache memory and a back end storage. In response to a detection of an event failure during an input/output (I/O) request from the host data processing system to the data storage system, the data associated with the I/O request is forwarded to the back end storage data, and a copy of the data associated with the I/O request is sent to the cache memory. A determination is made as to whether or not there is an acknowledgement from the back end storage regarding the receipt of the data associated with the I/O request. If there is an acknowledgement from the back end storage regarding the receipt of the data associated with the I/O request, the data associated with the I/O request is flushed from the cache memory, and the received acknowledgement is routed to the host data processing system.

Method and apparatus for controlling data storage within a data storage system

This specification concerns signal processing apparatus for processing line synchronization pulses in a line synchronization signal that define an analog video signal line period. The apparatus comprises a phase locked loop (40) for generating a clock signal of a frequency that is a multiple of the line synchronization signal frequency. The phase locked loop (40) comprises a counter (100) for dividing the clock signal by said multiple. The apparatus further comprises logic (110,50) for resetting the counter (100) upon detection of a spurious pulse introducing a time interval into the line synchronization signal of less than the line period of the video signal. The apparatus is particularly useful in image processing systems for digitizing analog video signals that have been replayed via a conventional, domestic video tape player, and therefore may comprise spurious line sync pulses introduced by playback head skip.

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Romsey, United Kingdom

Thomas W Rickard