ODA Reimage Survival Guide: Automatically Recreating Dozens of Databases Before RMAN Restore

One of the biggest challenges during an Oracle Database Appliance (ODA) OS reimage is that the process wipes out all appliance metadata, database homes, and database registrations. While RMAN backups protect the database contents, they do not recreate the ODA infrastructure required to host those databases.

Recently, I had to plan a reimage of an ODA cluster running Oracle 19c with more than 20 databases spread across multiple database homes. The main challenge was:

After reimaging the appliance, how do we quickly recreate all databases using odacli create-database without manually collecting and typing parameters for every database?

This article describes a simple and repeatable approach.

The Challenge

When an ODA is reimaged:

• Linux OS is rebuilt
• Grid Infrastructure is reinstalled
• ODA repository metadata is wiped out
• Database homes disappear
• Databases are no longer registered with ODA

After the reimage, the typical workflow is:

1. Recreate DB homes
2. Create empty databases using odacli create-database
3. Restore RMAN backups
4. Recover databases

For a handful of databases this is manageable.

For 20, 30, or more databases, manually recreating commands becomes both time-consuming and error-prone.

 

Required Information

To recreate a database using ODA, we need information similar to:

odacli create-database \

--dbname cisprep6 \

-u cisprep6 \

-cs UTF8 \

-cl OLTP \

--dbtype SI \

--no-cdb \

--target-node oda-node1 \

--dbshape Odb4 \

--dbstorage ASM \

-dh <DBHOMEID>

 

The challenge is collecting these attributes for every database before the reimage.

Exploring the ODA Repository

Oracle stores database metadata inside the internal MySQL repository.

Connect to the repository:

/opt/oracle/dcs/mysql/bin/mysql --defaults-file=/opt/oracle/dcs/mysql/etc/mysqldb.cnf

List tables:

use dcsagentdb;

show tables;

The most useful tables were:

Db,DBNode

Understanding Database Metadata

The db table contains most of the information required for recreation.

Example query:

select

name,

databaseUniqueName,

characterSet,

dbClass,

dbType,

dbShape,

isCdb,

dbTargetNodeNumber,

dbVersion,

dbStorage

from db;

 

Sample output

+----------+--------------------+--------------+

| name | databaseUniqueName | characterSet |

+----------+--------------------+--------------+

| edadev | edadev | UTF8 |

| edatest | edatest | UTF8 |

| soaiq56 | soaiq56 | AL32UTF8 |

+----------+--------------------+--------------+

Resolving Target Node Names

The db table stores only the node number:0,1

To map that value to the actual node name:

select nodeNumber,nodeName from DBNode;

Example

+------------+----------------+

| nodeNumber | nodeName |

+------------+----------------+

| 0 | oda-node1 |

| 1 | oda-node2 |

+------------+----------------+

Generating ODA Commands Automatically

Instead of manually creating commands, we can make MySQL generate them.

Example query:

SELECT CONCAT(

'odacli create-database ',

'--dbname ',d.name,' ',

'-u ',d.databaseUniqueName,' ',

'-cs ',d.characterSet,' ',

'-cl ',UPPER(d.dbClass),' ',

'--dbtype ',UPPER(d.dbType),' ',

IF(TRIM(IFNULL(d.isCdb,''))='YES',

'--cdb ',

'--no-cdb '

),

'--target-node ',n.nodeName,' ',

'--dbshape ',d.dbShape,' ',

'--dbstorage ',UPPER(d.dbStorage),' '

)

FROM db d

JOIN DBNode n

ON n.nodeNumber=d.dbTargetNodeNumber;

This generates ready-to-run odacli create-database commands.

Complete Automation Script

The following script generates a database recreation script automatically.

#!/bin/bash

DBHOMEID="<DBHOMEID>"

SCRIPT_NAME="create_database_$(hostname -s).sh"

/opt/oracle/dcs/mysql/bin/mysql \

--defaults-file=/opt/oracle/dcs/mysql/etc/mysqldb.cnf <<EOF > ${SCRIPT_NAME}

USE dcsagentdb;

SELECT CONCAT(

'odacli create-database ',

'--dbname ',d.name,' ',

'-u ',d.databaseUniqueName,' ',

'-cs ',d.characterSet,' ',

'-cl ',UPPER(d.dbClass),' ',

'--dbtype ',UPPER(d.dbType),' ',

IF(TRIM(IFNULL(d.isCdb,''))='YES',

'--cdb ',

'--no-cdb '

),

'--target-node ',n.nodeName,' ',

'--dbshape ',d.dbShape,' ',

'--dbstorage ',UPPER(d.dbStorage),' ',

'-dh ${DBHOMEID}'

)

FROM db d

JOIN DBNode n

ON n.nodeNumber=d.dbTargetNodeNumber;

EOF

sed -i '/^odacli/!d' ${SCRIPT_NAME}

chmod u+x ${SCRIPT_NAME}

echo "Generated: ${SCRIPT_NAME}"

 

Why This Helps

Instead of manually documenting:

• Database name
• Unique name
• Character set
• Database shape
• Storage type
• Target node
• CDB/Non-CDB status

for every database, the script extracts everything directly from the ODA repository.

For environments with 20+ databases, this can save several hours of manual effort and significantly reduce human errors.

 

Recommended Pre-Reimage Checklist

Before starting the ODA reimage:

✅ RMAN backups validated

✅ Database home inventory captured

✅ odacli list-dbhomes output saved

✅ Database recreation script generated

✅ TDE wallets backed up (if applicable)

✅ Listener and application connection information documented

✅ Database services documented

✅ Post-reimage DB home creation plan prepared

 

Final Thoughts

RMAN backups are only part of an ODA recovery strategy. During a full appliance reimage, the biggest challenge is often recreating the appliance metadata accurately and consistently. Leveraging the ODA repository itself to generate odacli create-database commands provides a simple, reliable, and highly scalable approach for environments hosting dozens of databases.

 

Same dbhome we can group together and run like below

 

 cat create_databases_test.sh

/opt/oracle/dcs/bin/odacli list-dbhomes

echo -n "Enter DBHOME-ID from the above list: "

read DBHOMEID

odacli create-database --dbname db1 -u db1 -cs UTF8 -cl OLTP --dbtype SI --no-cdb --target-node tuslsoda01b --dbshape Odb4 --dbstorage ASM -dh $DBHOMEID

odacli create-database --dbname db2 -u db2 -cs UTF8 -cl OLTP --dbtype SI --no-cdb --target-node tuslsoda01a --dbshape Odb2 --dbstorage ASM -dh $DBHOMEID

 

Only catch is we have to type password 2 times for every database as odacli does not gives any option to provide password as an argument…

 

I hope you have learned something useful