Log Shipping is one of the High Availability feature in SQL Server. In log-shipping log records are transfered from primary server to secondary server. When you configure log-shipping it required three servers but monitor server is optional. They are
- Primary server
- Secondary server
- Monitor server (Optional)
Client connecting to primary server and accessing database, at any time primary server crashed or down, manually fail-over to secondary server. Automation is not possible in log-shipping.
When you participate database in log-shipping it must be full/bulked recovery model only.
To get more information about log-shipping click on below link.