International Business Machines Corporation

David A Wise

Renata Rand McFadden

James M Showalter

Kevin C Huang

William James Schoen

John Lee Brooks

Application access to locally and remotely exported file systems is coordinated to allow caching data for exported file systems accessed by remote clients. In response to a request or file system access, it is determined whether the request relates to a locally exported file system or a remotely exported file system. If the request relates to a locally exported file system, a local access routine is invoked to obtain access permissions to the locally exported file system. If the request relates to remotely exported file system, a remote access routine is invoked to communicate with a local access routine in a file server responsible for coordinating access to the remotely exported file system to obtain access permissions to the remotely exported file system.

Method, computer program product, and system for coordinating access to locally and remotely exported file systems

Remote clients may access remotely exported file systems using a remote token manager that provides communication among a plurality of caching file servers. In response to a client request for file system access, a program is invoked to determine whether the request relates to a locally exported file system exported by a local caching file server or a remotely exported file system exported by a remote caching file server. If the request relates to a locally exported file system, a local token manager is invoked to obtain a token granting access permission to the locally exported file system. If the request relates to a remotely exported file system, a remote token manager is invoked to communicate with a local access routine in the remote caching file server to obtain a token granting access permission for the remotely exported file system.

Methods, computer program products, and apparatuses for providing remote client access to exported file systems

A set of trace data are generated for full tracing in private memory on a work unit basis. Generating the set of trace data includes source code having trace statements, where trace data based on the work unit includes either an identifier or a layer to establish a start and an end of the work unit, where either the identifier or the layer is specific to an application. Each trace data entry in the set of trace data created while executing a work unit contains a selection field to enable selecting which entries are transferred to the shared trace table from the private memory, when a work unit completes.

Systems, methods and computer products for trace capability per work unit

A computing system constructed of multiple processing elements containing private storage, attached to a shared global storage, is called a closely-coupled system. Each processing element may be a single processing unit (PU) with private storage, or a tightly coupled multi-processor unit with private storage. Either type of processing element will be referred to as a Central Processor Complex (CPC), the computing system complex as a whole is referred to as a sysplex. IBM ESA/390 processors provide examples of both single and multi-processor CPC's. For a highly-available shared storage for data-sharing in a multi-processing element environment, highly-available shared storage is provided by a duplexed controllers with non-volatile storage, which is accessed by tightly connected Processing Elements as a single logical copy. Our duplexed controllers provide not only the shared data but also the control information necessary for multi-Processing Element data management with speed-matching processor. The duplexed controllers, including a primary and backup controller, are always synchronized to execute each message command to ensure that they do not diverge. Each controller of the duplexed controller receives its own command from a Processing Element and reaches consensus with other controller to synchronize command execution and return a response code to the Processing Element. To sequence and synchronize the command execution by each of the duplexed controller, a tightly-synchronized Sysplex timer is used to time-stamp each command and response so that the duplexed controllers will run in synchronism. When an 'out of sync' condition is detected by a SSC, the monitoring information of SSC and integrated SP, and the result of diagnostics are used to determine the faulty SSC of a the duplexed SSC.

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New Paltz, NY, United States of America

David A Wise