After you have restored the mirror database and configured Data mirroring, when you start the mirroring it throws this error. The solution to resolving this is to restore the backup of the transaction log to the Mirror database. 1. Take backup of the TLOG at Principal site BACKUP LOG TO DISK = N'E:\transaction_log_bkp\Tlog_Bkp.trn' WITH NOFORMAT, … Continue reading The mirror database has insufficient transaction log data