International Business Machines Corporation

Radha R Kandadai

Robert J Curran

Frank Bernhard Schmuck

Chulho Kim

Robert Sidney Blackmore

James Christopher Wyllie

Gili Mendel

William A Kish

Gautam H Shah

Kuei-Yu Wang-Knop

Eugene Johnson

Anthony J Zlotek

Frank J Mangione

Boaz Shmueli

A method is provided for continuing node operations in quorum-based protocols. This is particularly valuable in the situation in which a group of nodes includes only two nodes and in which communications to a node is lost. Provision is made for adding additional status indications to each node indicating whether or not it is enabled for single-node quorum operation. Provision is also made for identifying one node as a primary node and another node as a secondary node for time-out response purposes.

Support for single-node quorum in a two-node nodeset for a shared disk parallel file system

In a multinode data processing system capable of partitioning operations a method is provided for adding nodes to a configuration of nodes in a manner which node quorums are employed but in which two quorum values (ideal and enforced) are employed and in which old nodes using a given file system are distinguished from new nodes. The method prevents even the transient use of inappropriate quorum values.

Dynamic quorum adjustment

Communication between different entities of a computing environment is facilitated by an address mapping capability. Messages are sent between the entities to have desired tasks performed. Instead of providing within the messages the actual non-logical addresses (e.g., virtual, real addresses) used to perform the tasks, logical addresses are provided. The logical addresses are then mapped to the non-logical addresses. Each logical address can map to a plurality of non-logical addresses.

Mapping a logical address to a plurality on non-logical addresses

A computer system having a shared disk file system running on multiple computers each having their own instance of an operating system and being coupled for parallel data sharing access to files residing on network attached shared disks. Locking techniques reduce the overhead of a token manager which is also used in the file system recovery if a computer participating in the management of shared disks becomes unavailable or failed. Synchronous and asynchronous takeover of a metadata node occurs for correction of metadata which was under modification and a new computer node to be a metadata node for that file. Locks are not constantly required to allocate new blocks on behalf of a user.

Parallel file system and method for independent metadata loggin

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Lake Katrine, NY, United States of America

Radha R Kandadai