Data Domain: AIR Event Stealing with Multiple NetBackup Domains Using Shared DDBoost Credentials

AIR replication jobs appeared successful, but some replicated backups could not be restored on the target environment.
Missing images were intermittent and could sometimes import successfully during a later attempt.
No AIR import errors were reported within NetBackup.
Disaster recovery testing revealed missing or unavailable backup images.
Multiple NetBackup domains were polling and processing event files from the same source and target LSU.
Data Domain logs contained event file rename activity associated with multiple NetBackup media servers.
DDBoost logs showed event file access attempts from unintended NetBackup domains.
Inconsistent AIR import behavior was observed after implementing multiple NetBackup domains.

The environment was configured with multiple NetBackup domains sharing the same Data Domain storage server and the same DDBoost user credentials. 
Because storage-unit visibility is tied to the DDBoost username, multiple NetBackup domains polled the same event directories and competed for the same AIR event files.
This created a race condition known as event stealing, where an unintended NetBackup media server consumed an AIR event intended for another domain. 
As a result, event files could be processed by the wrong NetBackup domain, leading to missing imports and inconsistent AIR behavior.
Log analysis confirmed that multiple NetBackup media servers were receiving and processing events for the same source and target LSU pair, which matches the known unsupported configuration scenario.

Verify whether multiple NetBackup domains are sharing the same Data Domain storage server and DDBoost credentials.
Review Data Domain ddfs.info logs for event file rename activity to identify whether multiple media servers are processing events for the same LSU pair.
Reconfigure the environment so NetBackup domains do not share the same DDBoost user account.
Assign unique DDBoost users and credentials to each NetBackup domain when using the same Data Domain system.
Ensure each NetBackup domain accesses only its designated storage units.
Eliminate overlapping event polling between domains to prevent event stealing and AIR import collisions.
Follow NetBackup and Data Domain supported configuration guidelines for AIR deployments.
Validation testing confirmed that using separate DDBoost credentials for each NetBackup domain resolved the issue and prevented future event-stealing scenarios.