CERNITDB Oracle Replication for RLS DBbackend Dirk Geppert
CERN/IT/DB Oracle Replication for RLS DB-backend Dirk Geppert
CERN/IT/DB Why Replication? q. Maximize Service Availability § Switch-over • Scheduled interventions § Fail-over • Unscheduled interventions § In combination with physical or logical `Standby’ DB? q. Need for Replicated Catalogs Nov 26, 2003 Dirk Geppert
CERN/IT/DB How to achieve this? q Replication § Master – Master • Synchronous, Asynchronous or Mixed-mode synchronous: transaction includes replication point of failure! • Setup – OEM Ø Database – Distributed – Advanced Replication – API Ø Oracle PL/SQL packages q Switch-/Failover Configuration § Server & Client side Oracle Net Configuration Nov 26, 2003 Dirk Geppert
CERN/IT/DB Replication ‘Master – Master’ q Master Group: build of `Master Sites’ DBs § ‘Master’ – ‘Primary’ ‘Master Site’ § ‘Standby’ – ‘Secondary’ ‘Master Site’ § Stop replication to add new master Scheduled! q Replicated Objects: build ‘Master Groups’ § object-level (tables, indexes, views, PL/SQL) § Once replicated, need DDL in replication framework q Push – via (deferred) Transaction Queues and Scheduled Jobs (via database links) Nov 26, 2003 Dirk Geppert
CERN/IT/DB Switch-/Failover q. Via ‘Oracle Net’ Configuration § Replication should always be possible § `Master – Master’ configuration • Clients may connect to both § `Primary – Standby’ configuration • Unnecessary client connections to ‘Standby’ should be avoided, only connections should be possible to the ‘Primary’ database Nov 26, 2003 Dirk Geppert
CERN/IT/DB Switch-/Failover 2 q Server-side § Master – Primary Master • 1 default-listener: replication and client connections § Standby – Secondary Master • 2 listeners – Replication (1526) UP – Client connections (1521) DOWN Manual Intervention, not automatic unless go for real ‘Master-Master’ q Client-side § 2 ‘addresses in address list’ and failover option Nov 26, 2003 Dirk Geppert
CERN/IT/DB Open Questions q Conflict resolution policies depending on replication setup and applications (RLS schema) q RLS schema modification? q App Server data source and connect string? q Trusted – Untrusted? § Propagator – Receiver: grants to access Master Group objects q Need pfile parameters for Replication: dynamically or restart of DB? Nov 26, 2003 Dirk Geppert
CERN/IT/DB Status & Next Steps q Setup done for toy schema q Test Switch-/Failover configurations q Implement for RLS environment § Tables, Constraints, Indexes, Triggers § Sequences: replication not supported! Modify schema i. e. sequences to be unique! (site prefix, range) § First quick tests show problems with SEQUENCES, TRIGGERS and CONSTRAINTS indexes (SYS_Cxxxxxx) schema modification for sequences q Check implications on e. g. performance q Provide API scripts q Implement & Test procedures for Fail-/Switchover Nov 26, 2003 Dirk Geppert
CERN/IT/DB Summary & Conclusions q Replication for § Switch-/Failover § Replicated catalogs q Setup and Configuration simple via OEM q Need to perform detailed tests for RLS § § RLS schema modifications RLS schema replication conflicts Implications on current service Define procedures (e. g. changes in configuration) Nov 26, 2003 Dirk Geppert
CERN/IT/DB Documentation q Metalink Top Tech Docs Database Distributed Master Replication § § § Concepts, Architecture and Design Setup Master Replication Configuration Administration Troubleshooting and Diagnostics q http: //metalink. oracle. com/metalink/plsql/ml 2_docum ents. show. Document? p_database_id=NOT&p_id=132 256. 1 Nov 26, 2003 Dirk Geppert
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