Microsoft SQL Server mirror database Error 1478

Question

Error msg: (Microsoft SQL Server, Error 1478): The mirror database has insufficient transaction log data to preserve the log backup chain of the principal database. This may happen if a log backup from the principal database has not been restored on the mirror database. 

Answer 1

Hi @Keke Yuan ，

When starting the synchronization for database mirroring, you may get the above error, mirroring requires a full restore and at least one tlog restore, the error is dur to the mirror database has insufficient transaction log data
To start the synchronization successfully, you can do following steps:

Principal Instance - - Take a full backup and a log backup as well, Copy the full/log backups from Principal Instance to Mirror instance
Mirror Instance - - Restore with NORECOVERY option the full backup
Mirror Instance - - Apply the log backup
Principal Instance - - Start synchronization

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