test-case-01 - OCI TAF Test

Tue, 18 Aug 2026 23:50:53 +0800

When designing a TAF (Transparent Application Failover) experiment in an Oracle 19c RAC environment, the key requirement is that the client must use an OCI-based (Oracle Call Interface) connection utility (such as SQL*Plus or custom OCI applications on Linux), as the JDBC Thin driver does not support TAF.

Below is a complete step-by-step guide for validating TAF via TNS on a Linux client.

1. Prerequisites
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Environment Requirements

Database: Oracle 19c RAC 2-node cluster (assuming nodes are node1 and node2, instance names are db1 and db2, and the service name is db175_svc).
Client OS: Linux with Oracle Client or Oracle Instant Client installed (including SQL*Plus and required OCI libraries).

Configure Client-Side TNS Settings Add the following TAF configuration to $ORACLE_HOME/network/admin/tnsnames.ora (or the Instant Client TNS directory) on your Linux client:

RAC_TAF =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (LOAD_BALANCE = yes)
      (ADDRESS = (PROTOCOL = TCP)(HOST = vm171-db01-vip.home.pollochang.work)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = vm172-db02-vip.home.pollochang.work)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = db175_svc)
      (FAILOVER_MODE =
        (TYPE = SELECT)
        (METHOD = BASIC)
        (RETRIES = 180)
        (DELAY = 5)
      )
    )
  )

TYPE = SELECT: When a node fails, the session switches to the surviving node, and in-flight SELECT queries continue fetching remaining rows without requiring manual re-execution.
METHOD = BASIC: Establishes a connection to the backup node only after a failure is detected.
RETRIES / DELAY: Configures the number of retry attempts and the delay interval in seconds.

Verify TNS Connectivity Run the following command in the Linux terminal:

`1`	`tnsping RAC_TAF`

Ensure the alias resolves properly and connects to the listener. 4. Create Test Data in the Database Log in with a DBA account and create a sufficiently large table (e.g., 1,000,000 rows) so you have enough time to simulate a node crash during query execution:

Work Notes on Pollo Tech Blog

test-case-01 - OCI TAF Test

1. Prerequisites #

1. Prerequisites
#