International Business Machines Corporation

Gregory L Morris

Mark John Baugher

Philip Y Chang

Alan Palmer Stephens

Everett Arthur McCassey, Ii

Steven Michael French

Daniel Dean Heimsoth

Ghassan A Yammine

Chun-tang Milton Li

A method for providing files to a remote node including the steps of determining whether bandwidth is available for transmitting across a communications link a file requested by a remote node, reserving bandwidth for the requested file if bandwidth is determined to be available, and opening the requested file for transmission only if bandwidth is reserved. In addition, an apparatus for providing files to a remote node including apparatus for determining whether bandwidth is available for transmitting across a communications link a file requested by a remote node, apparatus for reserving bandwidth for the requested file if bandwidth is determined to be available, and apparatus for opening the requested file for transmission only if bandwidth is reserved.

Method and apparatus for reserving system resources to assure quality of

A session-oriented local area network (LAN) application and an ISO 8802-2 protocol driver code will cooperate in a new form of connectionless, session-oriented communication called Sideband. At each session start-up time, the LAN Application will communicate with the enhanced ISO 8802-2 based protocol driver on the local system and the LAN Application and the 8802-2 based protocol driver on the remote system to determine if they all support the Sideband. If Sideband is fully supported by both systems, Sideband will be activated for the session. To communicate on a session which has Sideband active, the LAN Application requests that data is to be sent using the Sideband. A check is performed to see if the data meets Sideband criteria. As Sideband is a connectionless medium, the additional code path needed to set up and track timers and to handle the resend attempts are saved in the protocol. If the LAN Application code is session-oriented, it will keep track of a timer which will cause the data to be resent along a non-Sideband path if a response is not received within a designated amount of time. Header information is stored and reused to increase the throughput and decrease the response time for the transmission of small network packets. In case the network at some points becomes unreliable, procedures are used to track the reliability of the network and to enable and disable Sideband in accordance with the reliability of the network.

System for sending messages in a session using a mixture of protocols

A system and method for regeneration of certain on disk dynamic control blocks for the file system after failure of access to the control blocks improves auxiliary disk storage system robustness. Regeneration of the dynamic control blocks is achieved without persistent replicas of the blocks on disk and thereby adheres to prior art disk formats. The regeneration control blocks are preferably used to support file system operation during backup of the disk, since loss of access to critical sectors for storing control blocks may portend disk storage system failure.

System and method for maintaining file data access in case of dynamic

A session-oriented network application dependent on reliable transport of messages on a first system communicates in a new form of connectionless, session-oriented communication called Sideband over a network with a second similar application on a second system. Sideband transport is not guaranteed; Some types of messages and those which are lost must be sent on a reliable, non-Sideband transport. The LAN application contains means to track whether Sideband is both available and enabled on its session with the second application. The application determines whether to disable or reenable the Sideband in its session based on network reliability. As Sideband is fast, but unreliable, the application must be selective about which messages to send Sideband. Messages which would change the state of the receiving system if received twice due to retry of an apparently lost message should not be sent Sideband. The LAN application monitors the responses from the second system to determine whether any messages sent Sideband were lost. In the event of a Sideband message being lost, the application has retry logic which resends the message via a non-Sideband path.

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Round Rock, TX, United States of America

Gregory L Morris