Log Shipping

It is a database level high availability(HA). It runs through 4 jobs they are as follows

• Backup job
• Copy job
• Restore job
• Alert job

To configure this HA ie., log shipping we need three servers they are

• Primary server 
• Secondary server
• Monitor server(it's an optional server)

How Log Shipping will works?

Backup job: It will run on primary server. It will take the backups of the log transactions with frequent intervals(for every 15 mins) from primary database in to the network path/folder ie., shared folder. It will delete the old files more than 3 days(72 hours) from the same folder.

Copy job: Copy job will run from secondary server.Copy job will copy the files from backup folder to the local folder in the secondary server.It will  delete the older files more than 3 days.

Restore job: This job will run on secondary server. Restore job will restore the log files from local folder to secondary database.

Alert job: Alert job is created from monitor server, if monitor server is not configured then this job is created on both the servers(primary and secondary).One alert job is created per instance.It will send the alerts when the log shipping fails.