International Business Machines Corporation

William S Cadden

Rong S Lee

Oystein Skudal

David Alson George

Iwao Hatanaka

Stephen Craig Hughes

Anthony J Arcuri

Patricia E Heywood

Patrick Charles Mancuso

Laurence Howell Lancaster

Kurt A Riegel

Frederick P Muller

David W Stafford

Robert C Seacord

A technique is provided for facilitating writing of messages to multiple adapters connected to a high speed switch in a distributed computing environment. The technique employs a first, relatively quick filter to initially test whether a previously used adapter of the multiple adapters should be used to send a new message. If the first filter fails to select the previously used adapter, then the technique includes employing a second, more complicated filter to determine which adapter of the multiple adapters should be used to send the message. The first filter includes a first set of tests, and the second filter includes a second set of tests.

Technique for controlling selection of a write adapter from multiple adapters connected to a high speed switch

A technique is provided for facilitating peeking and reading of messages from multiple adapters connected, for example, to a high speed switch in a distributed computing environment. The technique employs a first, relatively quick filter to initially test whether a previously used adapter of the multiple adapters should be used to peek or read a new message. If the first filter fails to select the previously used adapter, then the technique includes employing a second, more complicated filter to determine which adapter of the multiple adapters should be used to peek or read the next message. The first filter includes a first set of tests, and the second filter includes a second set of tests.

Technique for controlling selection of a peek adapter or a read adapter from multiple adapters of a high speed switch

Technique for controlling selection of a peek adapter or a read adapter from multiple adapters connected to a high speed switch

Event handling in multinode data processing networks, in which data structures are shared between nodes and are subject to concurrent requests for access, is facilitated through the use of a separate small data structure (bit array or linked list) which permits an event handler to hand off the task of accessing the data structure to an event handler which is already accessing data from the same data structure. This eliminates the need for locking arrangements and/or the use of special coordinating event handlers.

Serializing event handling in a threaded system with no wait states

A write-behind computer program product is presented which allows writing data to multiple volumes of storage media associated with one or more server nodes in a distributed processing environment. A client application on a client node writes blocks of data to a first magnetic tape of a first server node until an end of physical storage of the first magnetic tape is reached, without having predetermined the size of the first magnetic storage. Thereafter, the writing of blocks of data is switched to a second magnetic tape, which may be on the first server node or a second server node in the system. The writing and switching process can repeat a number of times across multiple magnetic tapes. Data is written in a write-behind operation and the switching to a new magnetic tape occurs transparent to the client application, and without loss of data. The client and server nodes are adapted to ascertain how many blocks of data were written to the first storage medium, and the second storage medium, and to allow for the client process to write a header label to the second storage medium prior to writing blocks of data thereto.

Multi-volume, write-behind data storage in a distributed processing system

A write-behind enablement approach is presented which allows writing data to multiple volumes of storage media associated with one or more server nodes in a distributed processing environment. A client application on a client node writes blocks of data to a first magnetic tape of a first server node until an end of physical storage of the first magnetic tape is reached, without having predetermined the size of the first magnetic storage. Thereafter, the writing of blocks of data is switched to a second magnetic tape, which may be on the first server node or a second server node in the system. The writing and switching process can repeat a number of times across multiple magnetic tapes. Data is written in a write-behind operation and the switching to a new magnetic tape occurs transparent to the client application, and without loss of data. The client and server nodes are adapted to ascertain how many blocks of data were written to the first storage medium, and the second storage medium, and to allow for the client process to write a header label to the second storage medium prior to writing blocks of data thereto.

Method for multi-volume, write-behind data storage in a distributed processing system

System for multi-volume, write-behind data storage in a distributed processing system

Record-based backward skipping is provided for accessing logical records contained within physical blocks of data of a storage medium. A computing unit coupled to the storage medium reads a current block of data from the storage medium and determines a number of logical records within the current block, as well as the location of each logical record. The number of logical records is then employed to determine whether the desired logical record is within the current block, and if so, a pointer is provided to the desired logical record for skipping back to that record. If the desired logical record is not within the current block, then a previous block is read from the storage medium and the process is repeated to determine whether the desired logical record is within the new block.

Method for record-based backward skipping within physical blocks of data

System for record-based backward skipping within physical blocks of data

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Saugerties, NY, United States of America

William S Cadden