International Business Machines Corporation

Shin-Yuan Tzou

Jaishankar Moothedath Menon

James T Brady

Michael Howard Hartung

Michael Anthony Ko

Damon W Finney

David R Nowlen

Richard Francis Freitas

Noah R Mendelsohn

Alden B Johnson

Narasimhareddy L Annapareddy

John Chi-Shing Lui

A method and means are disclosed in a Log Structure Array (LSA) storage subsystem for managing said subsystem without a need for an access to a complete LSA directory in a RAM. This object is achieved by maintaining (1) a subset of the LSA directory (referred to as LSA sub-directory) in a RAM where the LSA sub-directory comprises the logical track address of a predetermined number of most recently accessed logical tracks; (2) a journal of changes to the LSA directory which is maintained on a different power boundary than the LSA directory power boundary; and, (3) an array of bit maps, one bit map per segment which is used for fast garbage collection thus eliminating the need for having an access to a complete LSA directory in a RAM during garbage collection.

Log structured array storage subsystem using LSA directory and LSA

A computing system includes plural nodes that are connected by a communications network. Each node comprises a communications interface that enables an exchange of messages with other nodes. A ready queue is maintained in a node and includes plural message entries, each message entry indicating an output message control data structure. The node further includes memory for storing plural output message control data structures, each including one or more chained further monrtol data structures that define data comprising a message or a portion of a message that is to be dispatched. Control data structures that are chained from an output messsage control data structure exhibit a sequence dependincy. A processor is controlled by the ready queue and enables dispatch of portions of the message designated by an output message control data structure and associated further control structures. The processor prevents dispatch of one portion of a message prior to dispatch of another portion of the message upon which the first portion is dependent even if message transmissions are interrupted.

System and method using chained structure queues for ordering of message

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San Jose, CA, United States of America

Shin-Yuan Tzou