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Backups on Standby DB failing with ERROR ORACLE DTC 21
Updated over a week ago

Problem description

  1. Primary and Standby are configured with Recovery Catalog

  2. Standby is registered with Druva for backup. Uses:

    1. OS Authentication

    2. Recovery catalog

  3. Structural change happens on primary database and logs are synced on standby

  4. Trigger backup on standby

  5. Backup fails with Oracle_DTC 21 error code.


This is because RMAN is able to connect to a standby database with a catalog user but unable to execute commands on it.


RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============    RMAN-00571: ===========================================================
RMAN-03002: failure of crosscheck command at 04/26/2023 12:00:34
RMAN-03014: implicit resync of recovery catalog failed
RMAN-03009: failure of partial resync command on default channel at 04/26/2023 12:00:34
ORA-17629: Cannot connect to the remote database server
ORA-17627: ORA-00942: table or view does not exist


  • Need to resync standby with primary database

๐Ÿ“ Note
โ€‹ Command to resync Connect to standby DB using catalog:
โ€‹ rman target sys/oracle@<tns_standby> catalog <cat_user>/<cat_pass>@<tns_catalog_db>;
Resync with primary DB:
โ€‹ r esync catalog from db_unique_name <db_unique_name_of_primary>;

  • Now the backup should work.

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