{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/22382"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/22382","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Quorum consensus protocols for the client server architecture","abstract":"In a client-server architecture, replicated copies of an object are assigned to different servers (possibly client sites) in order to increase the availability of the database in case some but not all servers fail. The aim of this work is to introduce a new highly efficient, highly reliable quorum consensus protocol, the Quorum Rings (QR) protocol, specifically designed to take advantage of the client-server architecture. We will also introduce an algorithm that modifies existing quorum consensus protocols to work efficiently and reliably with the client-server architecture. The high resiliency of the QR and the modified QC protocols is achieved at a very low cost in communication messages. More specifically, the number of communication messages required for a Read or Write operation is O(1) in normal mode (when there are no failures in the system), and only O($\\sqrt{N})$ (for the QR protocol) in failure mode when some but not all servers with replicated objects are faulty. Finally, the QR protocol exhibits the property of graceful degradation--more communication cost is incurred only when the number of failures increases in the system.","abstract_html":"In a client-server architecture, replicated copies of an object are assigned to different servers (possibly client sites) in order to increase the availability of the database in case some but not all servers fail. The aim of this work is to introduce a new highly efficient, highly reliable quorum consensus protocol, the Quorum Rings (QR) protocol, specifically designed to take advantage of the client-server architecture. We will also introduce an algorithm that modifies existing quorum consensus protocols to work efficiently and reliably with the client-server architecture. The high resiliency of the QR and the modified QC protocols is achieved at a very low cost in communication messages. More specifically, the number of communication messages required for a Read or Write operation is O(1) in normal mode (when there are no failures in the system), and only O($\\sqrt{N})$ (for the QR protocol) in failure mode when some but not all servers with replicated objects are faulty. Finally, the QR protocol exhibits the property of graceful degradation--more communication cost is incurred only when the number of failures increases in the system.","abstract_has_math":true,"creators":["Soufi, Khaled Saadi"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Computer Science","degree_department":null,"school":null,"contributors":["Belford, Geneva G."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T13:38:04Z","date_published":"2011-05-07T13:38:04Z","updated_at":"2026-07-22T22:25:19Z","subjects":["Computer Science"],"languages":["eng"],"rights":["Copyright 1994 Soufi, Khaled Saadi"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9512556","(UMI)AAI9512556"],"render_values":[{"text":"AAI9512556","href":null,"code":true},{"text":"(UMI)AAI9512556","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/22382","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Belford, Geneva G."]},{"key":"dc:creator","label":"Author","values":["Soufi, Khaled Saadi"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T13:38:04Z","10000-01-01","1994"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Computer Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Computer Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1994 Soufi, Khaled Saadi"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9512556","(UMI)AAI9512556","http://hdl.handle.net/2142/22382"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In a client-server architecture, replicated copies of an object are assigned to different servers (possibly client sites) in order to increase the availability of the database in case some but not all servers fail. 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