Hybrid migration follows ZDM's proven methodology of pre-check, data transfer, synchronization, and post-check. While there are manually several phases that ZDM goes through for a hybrid Migration, the overall workflow is summarized as follows:

1. ZDM connects to the source database and target database and performs the following validations:
   1. ZDM_VALIDATE_TGT phase: ZDM connects to the target database and performs validations.
   2. ZDM_VALIDATE_SRC phase: ZDM connects to the source database and performs validations.
   3. ZDM_SETUP_XTTS_SRC phase: ZDM configures required helper modules at the source level.
   4. ZDM_SETUP_XTTS_TGT phase: ZDM configures required helper modules at the target level.
2. ZDM orchestrates the tablespace-level backups:
   1. Performs a full backup of the tablespaces.
   2. Performs an incremental backup of the tablespaces.
   3. Copies the wallet files as required.
3. ZDM performs a full restore of tablespaces as foreign tablespaces.
4. ZDM sets the source tablespaces as read-only and performs the following steps:
   1. Performs an incremental backup of the tablespaces and metadata export of the tablespaces using RMAN.
   2. Copies the wallet files as required.
5. ZDM exports the metadata via Data Pump. The export includes:
   • Metadata
   • PL/SQL objects
   • Non-tablespaces data
6. ZDM imports the metadata and performs an incremental restore as follows:
   1. Import of the user metadata from Data Pump.
   2. Incremental restore with RMAN + import of tablespace metadata generated by RMAN.
   3. Import of all the other metadata (objects and non-tablespace data).
7. ZDM performs post actions, cleans up, and finalizes.

Zero Downtime Migration Service Host Requirements

For ZDM's service host requirements, installation, and overall configuration related information, refer to the Setting Up Zero Downtime Migration Software topic.

• The source and target databases must have the same time zone.
• The source and target databases must have the same character set and NLS character set.
• The source compatible version must be set to the same or a lower version than the target database.

• The target container database must not have any tablespaces sharing the same name as tablespaces at the source database. If a source database tablespace exists at the target level, then Data Pump will throw an error. Following are the other pre-requisites:
  • The source database must be at least Oracle Database 11.2.0.4.
  • This feature will only be available in Oracle Database 19c (19.24).

    For the target database, ensure that it contains the fix available in 35564253.

    Any source tablespace to be migrated should not exist on the target database, otherwise the Data Pump import will fail.

• SYSDBA is needed for hybrid migration source and target database users. This is because ZDM uses RMAN to run tablespace metadata import/export.

• For TDE encrypted source databases, with encrypted tablespaces, configure TDE at the target level as well.
• To provide the source and target TDE passwords, you can::
  • Use the ZDMCLI command line with zdmcli migrate database
    • -tdekeystorepasswd for the source database
    • -tgttdekeystorepasswd for the target database
  • Use the following response file parameters:
    • • WALLET_TDEKEYSTORE for the source database.
      • WALLET_TGTTDEKEYSTORE for the target database.
• Migrated unencrypted source databases will not result in an encrypted target database, you must perform the encryption at the target level post migration.

The NFS or shared storage between the source and the target database should have sufficient storage to hold all the RMAN backups and Data Pump dump files. You can specify the compression for the RMAN backups which should result in space reduction, however, conservatively, ensure that the space should be at-least as large as the size of the source database. You can specify the RMAN compression using the RMANSETTINGS_COMPRESSIONALGORITHM parameter.

The connectivity requirements for hybrid migration are same as physical and logical migration. You must have SSH connectivity for the source and target databases. You must have the SQL*Net connectivity between ZDM server and the source and the target database.

For SQL*Net setup, refer to the Physical and Logical Migration with SSH Access topic.

Create a response file after following the pre-requsites. Following is a sample file with the minimum required parameters. You can replace the parameters with values pertaining to your environment:

MIGRATION_METHOD=OFFLINE_XTTS DATA_TRANSFER_MEDIUM=NFS SOURCEDATABASE_ADMINUSERNAME= source database admin username SOURCEDATABASE_CONNECTIONDETAILS_HOST= hostname or ip address SOURCEDATABASE_CONNECTIONDETAILS_SERVICENAME= source service name or alias SOURCEDATABASE_CONNECTIONDETAILS_PORT= listener port number TARGETDATABASE_ADMINUSERNAME= source database admin username TARGETDATABASE_CONNECTIONDETAILS_HOST= hostname or ip address TARGETDATABASE_CONNECTIONDETAILS_PORT= listener port number TARGETDATABASE_CONNECTIONDETAILS_SERVICENAME= target service name or alias DATAPUMPSETTINGS_EXPORTDIRECTORYOBJECT_NAME= name of the directory object DATAPUMPSETTINGS_EXPORTDIRECTORYOBJECT_PATH= path of the directory object DATAPUMPSETTINGS_IMPORTDIRECTORYOBJECT_NAME= name of the directory object DATAPUMPSETTINGS_IMPORTDIRECTORYOBJECT_PATH= path of the directory object WALLET_TARGETADMIN= wallet path WALLET_SOURCEADMIN= wallet path

After following the pre-requsisites and after creating a response file, follow this sample migration command with the minimum required options and replace it with the values pertaining to your environment:

$ZDM_HOME/bin/zdmcli migrate database -sourcesid source_oracle_sid (use this parameter if the source is a single instance DB without Grid Infrasctructure) otherwise use -sourcedb source_db_unique_name_value (use this parameter is the source is configured with Grid Infrastructure) -sourcenode source-db-host-name -srcauth zdmauth -srcarg1 user:source_database_server_login_user_name -srcarg2 identity_file:ZDM_installed_user_private_key_file_location -srcarg3 sudo_location:/bin/sudo -targetnode target-db-host-name -rsp /home/zdmuser/hybrid_online.rsp -tgtauth zdmauth -tgtarg1 user:target_database_server_login_user_name -tgtarg2 identity_file:ZDM_installed_user_private_key_file_location -tgtarg3 sudo_location:/usr/bin/sudo 

For troubleshooting, review the following logs: