Setup Oracle Data Guard observer

This is the first time in several years that I've configured a DataGuard observer. See in the following how to install and configure Oracle Dataguard observer for Oracle database 19c (on Exadata @ OCI /ODB@AWS, should work similaron other envs making a difference just to be transparent here) Software installation has been done by my favorite tool: autoupgrade :-)

preps

install oracle preinstall

download the preinstall from public yum repo

wget https://yum.oracle.com/repo/OracleLinux/OL8/appstream/x86_64/getPackage/oracle-database-preinstall-19c-1.0-4.el8.x86_64.rpm

install with

sudo dnf localinstall oracle-database-preinstall-19c-1.0-4.el8.x86_64.rpm

I've faced an issue with the preinstalled bindutils version on my EC2 instance. I was not able to tell yum or dnf to omit the package with --no-best therefore I removed the bindutils manually with

sudo yum remove bind9.16-utils.x86_64

and was able to install oracle preinstall 19c package afterwards

install java & zip

autoupgrade needs an installed java and zip cli.

yum install zip -y
yum install java -y

autoupgrade etc

as we now have an oracle user we could switch to the oracle user and do our work with that user

mkdir autoupgrade

download autoupgrade

wget https://download.oracle.com/otn-pub/otn_software/autoupgrade.jar

create a config file for autoupgrade to download the software I've used autoupgrade composer by Marcus Vinicius to ease the config file creation.

touch download-19c.cfg

add the following (adapt if needed)

# Created by AutoUpgrade Composer
# AutoUpgrade Version: 26.6
# Patch, ExecMode: Download

global.global_log_dir=/home/oracle/autoupgrade/log
global.keystore=/home/oracle/autoupgrade/keystore

patch1.log_dir=/home/oracle/autoupgrade/log/patch1
patch1.download_folder=/home/oracle/autoupgrade/patches
patch1.patch=RU
patch1.target_version=19
patch1.platform=LINUX.X64

now we're nearly ready to download the patches first load the password to the keystore , for details see my other blog around autoupgrade

java -jar autoupgrade.jar -config download-19c.cfg -patch -load_password

let's download the patches:

java -jar autoupgrade.jar -config download-19c.cfg -patch -mode download

java -jar autoupgrade.jar -config download-19c.cfg -patch -mode download
AutoUpgrade Patching 26.6.260925 launched with default internal options
Processing config file ...
Loading AutoUpgrade Patching keystore
AutoUpgrade Patching keystore is loaded
AutoUpgrade Patching adds the MRP and OCW options to the PATCH configuration parameter because the generated Gold Image always includes those fixes.

Connected to Oracle Update Advisor service |- Requesting Gold Images 
AutoUpgrade Patching has finished processing the Gold Image requests

-----------------------------------------------------
Downloading files to /home/oracle/autoupgrade/patches
-----------------------------------------------------
DB Gold Image - 19.33.0.0.0
    File: db_goldimage_19_33_20261103131316.zip - VALIDATED
-----------------------------------------------------

let's go ahead and install the database home

create a new autoupgrade config

vi install-19c.cfg

add the following

# Created by AutoUpgrade Composer
# AutoUpgrade Version: 26.6
# Patch, ExecMode: CreateHome

global.global_log_dir=/home/oracle/autoupgrade/log

patch1.log_dir=/home/oracle/autoupgrade/log/DB1
patch1.download_folder=/home/oracle/autoupgrade/patches
patch1.patch=RU
patch1.target_version=19
patch1.target_home=/u00/app/oracle/product/%RELEASE%.%UPDATE%/dbhome_1
patch1.home_settings.edition=ee
patch1.home_settings.oracle_base=/u00/app/oracle
patch1.home_settings.inventory_location=/u00/app/oraInventory

java -jar autoupgrade.jar -config install-19.cfg -patch -mode create_home

the dataguard observer part

preps

create a small env file to have all the needed env vars set automatically

cat ora.env 
export ORACLE_HOME=/u00/app/oracle/product/19.33/dbhome_1/
export ORACLE_BASE=/u00/app/oracle/

export PATH=$PATH:$ORACLE_HOME/bin
export TNS_ADMIN=$ORACLE_HOME/network/admin

networking & db connectivity

configure tnsnames for primary and standby database

DG_SITE1 =
  (DESCRIPTION =
    (CONNECT_TIMEOUT = 120)
    (RETRY_COUNT = 3)
    (TRANSPORT_CONNECT_TIMEOUT = 90)
    (ADDRESS_LIST =
      (LOAD_BALANCE = yes)
      (ADDRESS = (PROTOCOL = TCP)(HOST = vmc-prd-01-scan.client.wjad0tl.oraclevcn.com)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = demo_site1.client.demo1.oraclevcn.com)
      (UR = A)
      (FAILOVER_MODE = (TYPE = select)(METHOD = basic))
    )
  )

DG_SITE2 =
  (DESCRIPTION =
    (CONNECT_TIMEOUT = 120)
    (RETRY_COUNT = 3)
    (TRANSPORT_CONNECT_TIMEOUT = 90)
    (ADDRESS_LIST =
      (LOAD_BALANCE = yes)
      (ADDRESS = (PROTOCOL = TCP)(HOST = vnc-stby-01-scan.client.demo2.oraclevcn.com(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = demo_site2.client.demo2.oraclevcn.com))
      (UR = A)
      (FAILOVER_MODE = (TYPE = select)(METHOD = basic))
    )
  )

tnsping to both sites above should be fine

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (CONNECT_TIMEOUT = 120) (RETRY_COUNT = 3) (TRANSPORT_CONNECT_TIMEOUT = 90) (ADDRESS_LIST = (LOAD_BALANCE = yes) (ADDRESS = (PROTOCOL = TCP)(HOST = vmc-prd-01-scan.client.wjad0tl.oraclevcn.com))(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = demo_site1.client.demo1.oraclevcn.com (UR = A) (FAILOVER_MODE = (TYPE = select)(METHOD = basic))))
OK (0 msec)

wallet config

as we're running on 19c observer includes the option to run in background. to achieve that we need to ensure passwordless authentication to the database is possible.

add the following to our sqlnet.ora

vi $TNS_ADMIN/sqlnet.ora

WALLET_LOCATION =
   (SOURCE =
      (METHOD = FILE)
      (METHOD_DATA = (DIRECTORY = /u00/app/oracle/admin/wallet))
)
SQLNET.WALLET_OVERRIDE = TRUE

create the wallet dir if it does not exist

mkdir /u00/app/oracle/admin/wallet

initialize a wallet (provide a password when prompted)

mkstore -wrl /u00/app/oracle/admin/wallet -create

store the passwords

mkstore -wrl /u00/app/oracle/admin/wallet -createCredential DG_SITE1 sys
mkstore -wrl /u00/app/oracle/admin/wallet -createCredential DG_SITE2 sys

mkstore -wrl /u00/app/oracle/admin/wallet -listCredential

test the connection

sqlplus /@DG_SITE1 as sysdba
sqlplus /@DG_SITE2 as sysdba

should be successful without a password prompt

observer config

create a directory to hold the configs

mkdir /u00/app/oracle/admin/fsfo

dgmgrl
connect /@dg_site1;

show configuration
enable fast_start failover;
Enabled in Potential Data Loss Mode.

now start the observer with (also in dgmrl)

start observer observer1 in background file is '/u00/app/oracle/admin/fsfoobserver1_dg.dat' logfile is '/u00/app/oracle/admin/fsfo/observer1.log' connect identifier is dg_site1;

output will look like

[...]
Submitted command "START OBSERVER" using connect identifier "DG_SITE1" 
DGMGRL> DGMGRL for Linux: Release 19.0.0.0.0 - Production on Wed Nov 4 10:35:35 2026
Version 19.33.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

[...]
Connected as SYSDBA.
Observer file "/u00/app/oracle/admin/fsfoobserver1_dg.dat" is created.
Succeeded in opening the observer file "/u00/app/oracle/admin/fsfoobserver1_dg.dat".
[W000 2026-11-04T10:35:38.522+00:00] FSFO target standby is DG_SITE2
Observer 'i-xxxx.eu-central-1.compute.internal1' started
The observer log file is '/u00/app/oracle/admin/fsfo/observer_dg1.log'.

Check the configuration (with dgmgrl)


show configuration

[...]

Fast-Start Failover: Enabled in Potential Data Loss Mode
  Lag Limit:          30 seconds
  Lag Type:           APPLY
  Threshold:          30 seconds
  Active Target:      DG_SITE2
  Potential Targets:  "DG_SITE2"
    DG_SITE2 valid
  Observer:           i-xxx.eu-central-1.compute.internal1
  Shutdown Primary:   TRUE
  Auto-reinstate:     TRUE
  Observer Reconnect: (none)
  Observer Override:  FALSE
  Lag Grace Time:     0 seconds

That's it :-) We've succesfully installed and configured DataGuard observer with the help of autoupgrade.