{"id":2276,"date":"2025-01-19T08:11:42","date_gmt":"2025-01-19T08:11:42","guid":{"rendered":"https:\/\/w3buddy.com\/?p=2276"},"modified":"2026-01-15T13:19:11","modified_gmt":"2026-01-15T07:49:11","slug":"oracle-data-guard-features-configuration-best-practices","status":"publish","type":"post","link":"https:\/\/w3buddy.com\/blog\/oracle-data-guard-features-configuration-best-practices\/","title":{"rendered":"Oracle Data Guard: Features, Configuration & Best Practices"},"content":{"rendered":"\n

Oracle Data Guard is a powerful feature for database high availability, disaster recovery, and data protection. This guide provides a detailed walkthrough of its features, types of standby databases, processes involved, configuration steps, and key commands. By the end of this post, you’ll have a deep understanding of Oracle Data Guard and how to manage it efficiently.<\/p>\n\n\n\n

Main Uses of Standby Databases<\/strong><\/h3>\n\n\n\n
Use Case<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
High Availability<\/strong><\/td>Ensures continuous availability of the database.<\/td><\/tr>
Data Protection<\/strong><\/td>Safeguards data through redundancy.<\/td><\/tr>
Disaster Recovery<\/strong><\/td>Provides recovery options during catastrophic events.<\/td><\/tr>
Backup Management<\/strong><\/td>Facilitates backups from standby databases.<\/td><\/tr>
Reporting<\/strong><\/td>Offloads reporting tasks to standby databases.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Types of Standby Databases<\/strong><\/h3>\n\n\n\n
Type<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Physical Standby<\/strong><\/td>– Exact block-for-block copy of the primary database.
– Maintained using REDO-APPLY<\/strong>.<\/td><\/tr>
Logical Standby<\/strong><\/td>– Converts data from the primary into SQL statements.
– Maintained using SQL-APPLY<\/strong> (LSP process applies redo).<\/td><\/tr>
Snapshot Standby<\/strong><\/td>– A fully updatable standby database converted from a physical standby.<\/td><\/tr>
Cascaded Standby<\/strong><\/td>– Receives redo logs from another standby to reduce primary system load.<\/td><\/tr>
Active Data Guard<\/strong><\/td>– Physical standby in read-only mode while applying redo.
– Enables reporting and RMAN backups on standby, offloading production load.<\/td><\/tr>
Transient Logical Standby<\/strong><\/td>– Supports rolling database upgrades by temporarily converting a physical standby to a logical standby.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Redo Transport Services<\/strong><\/h3>\n\n\n\n
Type<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Synchronous<\/strong><\/td>– Guarantees Zero Data Loss<\/strong>.
– Primary commits changes only after LNS<\/strong> confirms redo write on standby.<\/td><\/tr>
Asynchronous<\/strong><\/td>– Does not guarantee Zero Data Loss<\/strong>.
– LGWR<\/strong> does not wait for LNS<\/strong> confirmation.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Apply Services<\/strong><\/h3>\n\n\n\n
Type<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Real-time Apply<\/strong><\/td>– Used in physical standby databases.
– Applies changes as they are received without waiting for archiving.<\/td><\/tr>
SQL Apply<\/strong><\/td>– Converts redo data into SQL statements and applies them on a logical standby database.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Role Transitions<\/strong><\/h3>\n\n\n\n
Type<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Switchover<\/strong><\/td>– Switches roles between primary and standby.
– No data loss occurs.<\/td><\/tr>
Failover<\/strong><\/td>– Promotes standby to primary in case of primary failure.
– Risk of data loss if in MAXIMUM performance mode.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Affirm and Noaffirm<\/strong><\/h3>\n\n\n\n
Type<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Affirm<\/strong><\/td>– Ensures redo is written to the standby\u2019s disks.<\/td><\/tr>
Noaffirm<\/strong><\/td>– Ensures redo is received by one of the standby databases.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Protection Modes<\/strong><\/h3>\n\n\n\n
Mode<\/strong><\/th>Transport Method<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Maximum Protection<\/strong><\/td>SYNC \/ LGWR<\/td>– Guarantees Zero Data Loss<\/strong>.
– Shuts down primary if redo cannot be written to standby.<\/td><\/tr>
Maximum Availability<\/strong><\/td>SYNC \/ LGWR<\/td>– Operates like MAXIMUM PROTECTION but allows primary to continue if standby synchronization fails temporarily.<\/td><\/tr>
Maximum Performance<\/strong><\/td>ASYNC \/ LGWR \/ ARCH<\/td>– Focuses on performance, with minimal data loss in normal operation.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Physical Standby Database Related Processes<\/strong><\/h3>\n\n\n\n
Database<\/strong><\/th>Process<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Primary Database<\/strong><\/td>LGWR<\/strong><\/td>Log Writer flushes log buffers from the SGA to Online Redo Log files.<\/td><\/tr>
<\/td>LNS<\/strong><\/td>LogWriter Network Service reads redo flushed by LGWR and sends it over the network to the standby.<\/td><\/tr>
<\/td>ARCH<\/strong><\/td>Archives Online Redo Log (ORL) files to archive log files.<\/td><\/tr>
Standby Database<\/strong><\/td>RFS<\/strong><\/td>Remote File Server receives redo from the primary, writes it to Standby Redo Log (SRL) files.<\/td><\/tr>
<\/td>ARCH<\/strong><\/td>Archives SRL files into archived log files, similar to primary database.<\/td><\/tr>
<\/td>MRP<\/strong><\/td>Managed Recovery Process coordinates media recovery management.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Data Guard Broker Configuration<\/strong><\/h3>\n\n\n\n
Step<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
Purpose<\/strong><\/td>Provides unified administration for Data Guard, including switchover and failover.<\/td><\/tr>
Configuration Files<\/strong><\/td>Maintains information in flat files, with redundant copies stored on each database in the Data Guard configuration.<\/td><\/tr>
Parameters<\/strong><\/td>Controlled by:
– DG_BROKER_CONFIG_FILE_1<\/code>
– DG_BROKER_CONFIG_FILE_2<\/code>.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Configuration Steps<\/strong><\/h3>\n\n\n\n
Step<\/strong><\/th>Commands\/Actions<\/strong><\/th><\/tr><\/thead>
1. Configure Parameters<\/strong><\/td>Primary:<\/strong>
– ALTER SYSTEM SET dg_broker_config_file_1='path';<\/code>
– ALTER SYSTEM SET dg_broker_config_file_2='path';<\/code>
– ALTER SYSTEM SET dg_broker_start=TRUE SCOPE=BOTH;<\/code>
– ALTER SYSTEM SET local_listener='';<\/code>
Standby:<\/strong>
Repeat the same steps on the standby database.<\/td><\/tr>
2. Verify TNS<\/strong><\/td>Ensure connectivity between the primary (tns_prod<\/code>) and standby (tns_stby<\/code>).<\/td><\/tr>
3. Configure DGMGRL<\/strong><\/td>Commands:<\/strong>
– dgmgrl<\/code>
– CONNECT sys\/password@tns_prod<\/code>
– CONNECT sys\/password@tns_stby<\/code>
– SHOW CONFIGURATION<\/code><\/td><\/tr>
4. Create Configuration<\/strong><\/td>Primary:<\/strong>
CREATE CONFIGURATION 'PROD' AS PRIMARY DATABASE IS 'PROD_DB' CONNECT IDENTIFIER IS 'tns_prod';<\/code>
Ensure LOG_ARCHIVE_DEST_2<\/code> is empty.<\/td><\/tr>
5. Add Standby<\/strong><\/td>ADD DATABASE 'DR' AS CONNECT IDENTIFIER IS 'DR';<\/code><\/td><\/tr>
6. Enable Configuration<\/strong><\/td>ENABLE CONFIGURATION;<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Switchover and Switchback Commands Using DGMGRL<\/strong><\/h3>\n\n\n\n
Action<\/strong><\/th>Command<\/strong><\/th><\/tr><\/thead>
Perform Switchover to Standby<\/strong><\/td>SWITCHOVER TO DR;<\/code><\/td><\/tr>
Convert Standby to Snapshot Standby<\/strong><\/td>CONVERT DATABASE 'DR' TO SNAPSHOT STANDBY;<\/code><\/td><\/tr>
Convert Back to Physical Standby<\/strong><\/td>CONVERT DATABASE 'DR' TO PHYSICAL STANDBY;<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Useful Commands to Show Data Guard Configuration<\/strong><\/h3>\n\n\n\n
Command<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
SHOW CONFIGURATION;<\/code><\/td>Displays the overall Data Guard configuration.<\/td><\/tr>
SHOW CONFIGURATION VERBOSE;<\/code><\/td>Provides detailed information about the configuration.<\/td><\/tr>
SHOW DATABASE 'PRIM';<\/code><\/td>Displays details of the primary database.<\/td><\/tr>
SHOW DATABASE VERBOSE 'PRIM';<\/code><\/td>Provides detailed information about the primary database.<\/td><\/tr>
VALIDATE DATABASE 'PRIM';<\/code><\/td>Validates the primary database setup.<\/td><\/tr>
VALIDATE DATABASE VERBOSE 'PRIM';<\/code><\/td>Provides detailed validation output for the primary database.<\/td><\/tr>
SHOW DATABASE 'PRIM' SENDQENTRIES;<\/code><\/td>Shows the send queue entries for the primary database.<\/td><\/tr>
SHOW DATABASE 'DR' RECVQENTRIES;<\/code><\/td>Shows the receive queue entries for the standby database.<\/td><\/tr>
VALIDATE NETWORK CONFIGURATION FOR ALL;<\/code><\/td>Validates the network configuration for all databases<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Edit Database Properties<\/strong><\/h3>\n\n\n\n
Action<\/strong><\/th>Command<\/strong><\/th><\/tr><\/thead>
Disable Apply Mode<\/strong><\/td>EDIT DATABASE 'DR' SET STATE='APPLY-OFF';<\/code><\/td><\/tr>
Disable Transport Mode<\/strong><\/td>EDIT DATABASE 'DR' SET STATE='TRANSPORT-OFF';<\/code><\/td><\/tr>
Enable Apply Mode<\/strong><\/td>EDIT DATABASE 'DR' SET STATE='APPLY-ON';<\/code><\/td><\/tr>
Enable Transport Mode<\/strong><\/td>EDIT DATABASE 'DR' SET STATE='TRANSPORT-ON';<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Change Protection Mode<\/strong><\/h3>\n\n\n\n
Action<\/strong><\/th>Command<\/strong><\/th><\/tr><\/thead>
Change Log Transport to Synchronous<\/strong><\/td>EDIT DATABASE 'chennai' SET PROPERTY 'LogXptMode'='SYNC';<\/code><\/td><\/tr>
<\/td>EDIT DATABASE 'delhi' SET PROPERTY 'LogXptMode'='SYNC';<\/code><\/td><\/tr>
Set Protection Mode to Max Availability<\/strong><\/td>EDIT CONFIGURATION SET PROTECTION MODE AS MAXAVAILABILITY;<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Enable Fast-Start Failover<\/strong><\/h3>\n\n\n\n
Step<\/strong><\/th>Command<\/strong><\/th><\/tr><\/thead>
Ensure Protection Mode<\/strong><\/td>Set to MAX AVAILABILITY<\/strong>.<\/td><\/tr>
Enable Fast-Start Failover<\/strong><\/td>ENABLE FAST_START FAILOVER;<\/code><\/td><\/tr>
Show Fast-Start Failover Status<\/strong><\/td>SHOW FAST_START FAILOVER;<\/code><\/td><\/tr>
Start Observer<\/strong><\/td>nohup dgmgrl sys\/oracle@orcl \"start observer file='\/home\/oracle\/fsfo.dat'\" -logfile $HOME\/observer.log &<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"

Oracle Data Guard is a powerful feature for database high availability, disaster recovery, and data protection. This guide provides a detailed walkthrough of its features, types of standby databases, processes involved, configuration steps, and key commands. By the end of this post, you’ll have a deep understanding of Oracle Data Guard and how to manage […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"googlesitekit_rrm_CAowu461DA:productID":"","footnotes":""},"categories":[1225],"tags":[],"class_list":["post-2276","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/2276","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/comments?post=2276"}],"version-history":[{"count":1,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/2276\/revisions"}],"predecessor-version":[{"id":2278,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/2276\/revisions\/2278"}],"wp:attachment":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/media?parent=2276"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/categories?post=2276"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/tags?post=2276"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}