International Business Machines Corporation

Samuel E Reynolds

Roy Frank Brabson

Wesley McMillan Devine

Wayne Erwin Rhoten

Kimberly Tekavec Bailey

Patrick Gerald Brown

David Glenn George

Ralph Benjamin Case

Johnathan L Harter

Andrew K Tracy

A method, system, and computer program product for managing a storage facility are disclosed. A potential file overlay may be detected when performing a file transfer. When a file is common to multiple systems and resides on a shared system storage volume, potential file corruption due to a data transfer request is detected and then able to be prevented. Hardware identifiers such as Universal Unique Identifiers (UUIDs) are used in managing a write of a file to shared system storage. By comparing multiple hardware identifiers, a determination is made as to whether to process the write of the file. If the hardware identifiers mismatch, the write is processed. If the hardware identifiers match, a potential file overlay is detected. Because of the potential file overlay, the write is aborted and a failure notification is returned. A successful overwrite prevention notification may also be returned.

Managing a shared storage system using hardware identifiers to deter data/file corruption

An improved technique is disclosed for routing data across multiple topology subnets, and for improving the connectivity between nodes in multiple topology subnets, by using a common connection network. A new type of virtual node, referred to herein as a 'global' virtual routing node or 'GVRN', is defined to represent connectivity to an underlying network that may extend beyond the boundaries of the topology subnets in the end-to-end path. This underlying network is also referred to as a &#x201c;common connection network&#x201d; or a &#x201c;global connection network&#x201d;. The present invention also defines novel techniques with which border nodes pass routing information between networks to convey connectivity to the GVRN. In many cases, use of GVRNs will result in shorter end-to-end data transmission paths.

Efficient connectivity between multiple topology subnets via common connection network

A timing control mechanism designed for a high performance network wherein many of the timers are cancelled or reset prior to expiring. This method and apparatus enable the cancels and resets to occur with minimal impact to the system performance. An intermediate work queue is used, where timer events are posted prior to being scheduled into the timer queues by the timer process. Thus, many of the cancels or resets will be implemented simply by changing the status of events in this work queue, minimizing the impact on the timer queues and timers. The timer process processes the work queue before processing any timer events.

Timer state control optimized for frequent cancel and reset operations

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Apex, NC, United States of America

Samuel E Reynolds