HP IT-Symposium 2006 “This presentation is for informational purposes only and may not be incorporated into a contract or agreement.” This document is for informational purposes. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described in this document remains at the sole discretion of Oracle. This document in any form, software or printed matter, contains proprietary information that is the exclusive property of Oracle. This document and information contained herein may not be disclosed, copied, reproduced or distributed to anyone outside Oracle without prior written consent of Oracle. This document is not part of your license agreement nor can it be incorporated into any contractual agreement with Oracle or its subsidiaries or affiliates. Page 1 www.decus.de 1
HP IT-Symposium 2006 Automatic Failover across sites with Data Guard Fast-Start Failover DECUS, Duesseldorf 2006 Larry M. Carpenter Principal Product Manager High Availability & Disaster Recovery Oracle USA Page 2 www.decus.de 2
HP IT-Symposium 2006 Agenda • A quick look at Data Guard • How do users perform Failover today? • Fast-Start Failover – An Overview • Fast-Start Failover – The Details • Client Failover • User Experiences A quick look at Data Guard Page 3 www.decus.de 3
HP IT-Symposium 2006 What is Oracle Data Guard? • Oracle’s Disaster Recovery solution for Oracle. • A Feature of Oracle Database Enterprise Edition • Automates the creation and maintenance of one or more transactionally consistent Standby databases. • Provides comprehensive role management. • Role transitions • Standby to Primary and back to Standby • For planned and unplanned outages A Data Guard Configuration Standby Site A Primary Site Standby Site B Broker Standby Database Primary Database Standby Database • Managed as a single configuration • Primary and standby databases can be Real Application Clusters or single-instance Oracle • Up to nine standby databases supported in a single configuration Page 4 www.decus.de 4
HP IT-Symposium 2006 How do users perform Failover today? Failover Implications • Faster is better - Downtime is bad • If manual intervention is required, the time it takes to notify administrative staff can be lengthy • Reliability is a must-have • Correct procedure for failover must be followed to meet data loss (recovery point) objective • Simplicity is preferred • Determining if failure condition warrants failover adds time & complexity to the failover process Page 5 www.decus.de 5
HP IT-Symposium 2006 Best Practice Add Standby Redo Logs • A separate pool of log file groups on a standby site • Used just like the online redo logs on a primary • Requires local archiving on the standby database • Requires same size and number of Primary database online redo logs but more is better • Cannot be assigned to a thread in 9 i • Are required for Zero Data loss configurations as of Oracle Database10 g Release 1. SRL Architecture Standby Archived Redo Redo Redo from primary Logs Logs database LGWR RFS ARCH New! 10 g Physical ARCH RFS & Logical 10 g standby databases Page 6 www.decus.de 6
HP IT-Symposium 2006 Benefits • Better Performance • Standby redo logs are pre-allocated files • Can reside on raw devices • Better Protection • Can have multiple members • If primary database failure occurs, redo data written to standby redo logs can be fully recovered. Failover • Failover needed when switchover not possible • i.e. The primary is gone! • Same basic steps as switchover but some processing might be done manually • Remember! • Don’t plan for DR by expecting to be able to return to the Primary and ‘get’ something. • You won’t be able to ‘get’ anything. Page 7 www.decus.de 7
HP IT-Symposium 2006 Choose a Standby • Choose a standby site with the most up to date redo information • If Primary was ‘protected’ then one site must have the ‘latest’ redo information in its Standby On-line Redo logs • Archive Log file ‘GAPs’ at this site must be resolved from the other standby sites • Choose a Physical and other standby databases will come along if possible. • Choose a Logical and none of the other standby databases can come along Physical Standby Failover Page 8 www.decus.de 8
HP IT-Symposium 2006 Failover to a Physical Standby Primary Physical Standby Database Database ALTER DATABASE RECOVER 1 MANAGED STANDBY DATABASE FINISH; 2 ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; 3 RESTART DATABASE 10.2.0.1 Step 1 Improvements • In Oracle Database10 g Release 2 • New FORCE keyword • RECOVER MANAGED STANDBY DATABASE FINISH FORCE; • The new FORCE option stops active RFS processes on the target standby database so the failover will proceed immediately, without waiting for network connections to time out, once logs have been applied. • SQLNET.EXPIRE_TIME no longer necessary. Page 9 www.decus.de 9
HP IT-Symposium 2006 10.2.0.1 Step 3 Improvements • In Oracle Database10 g Release 2 • No longer necessary to restart the Standby for it to become the Primary, just do an: • ALTER DATABASE OPEN; • Requires that the standby was not opened read only since it was last started. • Speeds up failover time considerably. 10.2.0.1 Failover to a Physical Standby Primary Physical Standby Database Database ALTER DATABASE RECOVER 1 MANAGED STANDBY DATABASE FINISH FORCE; 2 ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; 3 ALTER DATABASE OPEN; Page 10 www.decus.de 10
HP IT-Symposium 2006 Logical Standby Failover Failover to a Logical Standby Primary Logical Standby Database Database ALTER DATABASE STOP LOGICAL 1 STANDBY APPLY; ALTER DATABASE START 2 LOGICAL STANDBY APPLY FINISH; ALTER DATABASE STOP LOGICAL 3 STANDBY APPLY; 4 ALTER DATABASE ACTIVATE LOGICAL STANDBY DATABASE; Page 11 www.decus.de 11
HP IT-Symposium 2006 10.2.0.1 Reduced Steps • In Oracle Database10 g Release 2 • Apply finish and failover now in one command. • No longer necessary to start or stop the Apply. 10.2.0.1 Failover to a Logical Standby Primary Logical Standby Database Database ALTER DATABASE ACTIVATE 1 LOGICAL STANDBY DATABASE FINISH APPLY; Page 12 www.decus.de 12
HP IT-Symposium 2006 Using the Data Guard Broker One Step always! • Login to DGMGRL by connecting to any surviving database in the configuration • And execute the failover! • DGMGRL> FAILOVER TO <database>; • You still need to decide which standby to use as the target of the failover! Page 13 www.decus.de 13
HP IT-Symposium 2006 What about Grid Control? Page 14 www.decus.de 14
HP IT-Symposium 2006 Fast-Start Failover Eliminate the Manual Steps! Remember the Requirements? • Faster is better - Downtime is bad? • Site failover time measured in seconds • Not minutes • Failover is automatic, no manual intervention • Reliability is a must-have? • Eliminates human error • Simplicity is preferred? • Automatically determines if failover criteria met • Original primary database is automatically reinstated as a new standby database. Page 15 www.decus.de 15
HP IT-Symposium 2006 Fast-Start Failover Architecture Observer • Primary Database Primary Site Standby Site • Target Standby Database • Observer Process database database Fast-Start Failover The Details Page 16 www.decus.de 16
HP IT-Symposium 2006 Fast-Start Failover Requirements • Primary and Standby are managed by the Data Guard Broker • Primary database must be in Maximum Availability mode • Primary and standby must have Flashback Database enabled • Observer host must have DGMGRL utility installed and must have Oracle Net connectivity to both the primary and standby Setting it up using Grid Control Page 17 www.decus.de 17
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HP IT-Symposium 2006 Using the Broker Directly DGMGRL command line interface Set the Target and Threshold • Configure “FastStartFailoverTarget” is the “ DB_UNIQUE_NAME” of the • target standby database. Using DGMGRL; • DGMGRL> EDIT DATABASE 'North_Sales‘ SET PROPERTY FastStartFailoverTarget =‘DR_Sales’; “FastStartFailoverThreshold” is the Number of seconds • Observer attempts to reconnect to the primary database before initiating fast-start failover • DGMGRL> EDIT CONFIGURATION SET PROPERTY FastStartFailoverThreshold = 45; Page 23 www.decus.de 23
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