SQL Server Log shipping allows you to automatically send transaction log backups from a primary database on a primary server instance to one or more secondary databases on separate secondary server instances. The transaction log backups are applied to each of the secondary databases individually. An optional third server instance, known as the monitor server, records the history and status of backup and restore operations and, optionally, raises alerts if these operations fail to occur as scheduled.
- Provides a disaster-recovery solution for a single primary database and one or more secondary databases, each on a separate instance of SQL Server.
- Supports limited read-only access to secondary databases (during the interval between restore jobs).
- Allows a user-specified delay between when the primary server backs up the log of the primary database and when the secondary servers must restore (apply) the log backup. A longer delay can be useful, for example, if data is accidentally changed on the primary database. If the accidental change is noticed quickly, a delay can let you retrieve still unchanged data from a secondary database before the change is reflected there.
Log Shipping Overview
Log shipping consists of three operations:
- Back up the transaction log at the primary server instance.
- Copy the transaction log file to the secondary server instance.
- Restore the log backup on the secondary server instance.
The log can be shipped to multiple secondary server instances. In such cases, operations 2 and 3 are duplicated for each secondary server instance.
A log shipping configuration does not automatically fail over from the primary server to the secondary server. If the primary database becomes unavailable, any of the secondary databases can be brought online manually.
You can use a secondary database for reporting purposes.
In addition, you can configure alerts for your log shipping configuration.