Troubleshooting Out of Sync Error in Log Shipping

Troubleshooting Out of Sync Error in Log Shipping

Log shipping uses Sqlmaint.exe to back up and to restore databases. When SQL Server creates a transaction log backup as part of a log shipping setup, Sqlmaint.exe connects to the monitor server and updates the log_shipping_primaries table with the last_backup_filename information. Similarly, when you run a Copy or a Restore job on a secondary server, Sqlmaint.exe connects to the monitor server and updates the log_shipping_secondaries table.

As part of log shipping, alert messages 14220 and 14221 are generated to track backup and restoration activity. The alert messages are generated depending on the value of Backup Alert threshold and Out of Sync Alert threshold respectively.

The alert message 14220 indicates that the difference between current time and the time indicated by the last_backup_filename value in the log_shipping_primaries table on the monitor server is greater than value that is set for the Backup Alert threshold.

The alert message 14221 indicates that the difference between the time indicated by the last_backup_filename in the log_shipping_primaries table and the last_loaded_filename in the log_shipping_secondaries table is greater than the value set for the Out of Sync Alert threshold.

Troubleshooting Error Message 14420

By definition, message 14420 does not necessarily indicate a problem with log shipping. The message indicates that the difference between the last backed up file and current time on the monitor server is greater than the time that is set for the Backup Alert threshold.

There are serveral reasons why the alert message is generated. The following list includes some of these reasons:

1. The date or time (or both) on the monitor server is different from the date or time on the primary server. It is also possible that the system date or time was modified on the monitor or the primary server. This may also generate alert messages.
2. When the monitor server is offline and then back online, the fields in the log_shipping_primaries table are not updated with the current values before the alert message job runs.
3. The log shipping Copy job that is run on the primary server might not connect to the monitor server msdb database to update the fields in the log_shipping_primaries table. This may be the result of an authentication problem between the monitor server and the primary server.
4. You may have set an incorrect value for the Backup Alert threshold. Ideally, you must set this value to at least three times the frequency of the backup job. If you change the frequency of the backup job after log shipping is configured and functional, you must update the value of theBackup Alert threshold accordingly.
5. The backup job on the primary server is failing. In this case, check the job history for the backup job to see a reason for the failure.

Troubleshooting Error Message 14421

By definition, message 14421 does not necessarily indicate a problem with Log Shipping. This message indicates that the difference between the last backed up file and last restored file is greater than the time selected for the Out of Sync Alert threshold.

There are serveral reasons why the alert message is raised. The following list includes some of these reasons:

1. The date or time (or both) on the primary server is modified such that the date or time on the primary server is significantly ahead between consecutive transaction log backups.
2. The log shipping Restore job that is running on the secondary server cannot connect to the monitor server msdb database to update the log_shipping_secondaries table with the correct value. This may be the result of an authentication problem between the secondary server and the monitor server.
3. You may have set an incorrect value for the Out of Sync Alert threshold. Ideally, you must set this value to at least three times the frequency of the slower of the Copy and Restore jobs. If the frequency of the Copy or Restore jobs is modified after log shipping is set up and functional, you must modify the value of the Out of Sync Alert threshold accordingly.
4. Problems either with the Backup job or Copy job are most likely to result in "out of sync" alert messages. If "out of sync" alert messages are raised and if there are no problems with the Backup or the Restore job, check the Copy job for potential problems. Additionally, network connectivity may cause the Copy job to fail.
5. It is also possible that the Restore job on the secondary server is failing. In this case, check the job history for the Restore job because it may indicate a reason for the failure.