Step-by-Step Guide: Configure Transparent Application Continuity (TAC) in Oracle RAC
Oracle’s Transparent Application Continuity (TAC) is a powerful feature that enhances high availability by automatically recovering failed database sessions without requiring application changes. In an Oracle RAC environment, TAC ensures uninterrupted transactions even during node failures.
This guide walks you through configuring TAC in an Oracle RAC environment with a Container Database (CDB) and Pluggable Database (PDB).
Environment Overview
– DB Name: prim
– CDB with PDB: pdbprim
– Nodes: prim1, prim2
– Service Name: prim_tac_svc
– SCAN Host: node-scan
– User: pdbuser
– Table for Demo: test_table
1. Create the TAC-Enabled Service
Run the following as the grid user:
srvctl add service -db prim \
-service prim_tac_svc \
-pdb pdbprim \
-preferred prim2,prim1 \
-failovertype AUTO \
-failover_restore AUTO \
-failoverdelay 5 \
-failoverretry 30 \
-commit_outcome TRUE \
-replay_init_time 600
2. Verify the Service Configuration
srvctl config service -db prim -service prim_tac_svc
3. Start the Service
srvctl start service -db prim -service prim_tac_svc
4. Create TNS Entry (on Client Side)
In tnsnames.ora:
TAC_PRIM =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = node-scan)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = prim_tac_svc)
)
)
5. Simulate the issueby creating Oracle table and Python Script
CREATE TABLE u1.ac_test ( id NUMBER PRIMARY KEY, data VARCHAR2(200) );
Important Notes
– Application doesn’t require code changes but must use Oracle-supported drivers like JDBC, ODP.NET, Oracle Call Interface, etc.
– Replay buffers the session to memory; long idle sessions may not be eligible.
– Works best when the app uses services with TAC setup, not just SYSDBA logins.
Final Thoughts
Transparent Application Continuity (TAC) is a powerful feature for increasing uptime and user satisfaction. Whether it’s a planned maintenance or an unplanned outage, TAC ensures that your application doesn’t feel the impact.
If you want to learn more or practice this in a live environment, check out Learnomate Technologies for labs, videos, and expert guidance!
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