Summary

Log shipping is a simple, inexpensive, dependable SQL Server high-availability solution with a long track record. As a disaster recovery solution, it has been deployed to maintain a standby server over a distance for business continuity to protect from a local disaster, power-grid failure, and network outages. Log shipping can ship the log anywhere in the world. Its only limitation is the network bandwidth capacity to transfer the transaction log file in a timely manner. It can be combined with a reporting solution when an organization requires point-in-time reporting rather than real time. Moreover, it has been deployed as an alternative to Windows failover clustering to provide a local, high-availability solution, where it is less expensive to implement, as it does not require a shared disk system. The challenge for deploying log shipping is that it does not provide any automatic client redirect; therefore, an operator needs to have an approach for it. In addition, the role switch requires some user intervention to ensure that all of the transaction logs have been restored to the standby server. Switching the roles back also requires some manual intervention. Another challenge is that log shipping is at the user database level and does not copy new logins, database users, SQL jobs, Integration Services, or DTS packages from the primary server. But using Integration Services' Tasks and SQL Agent jobs, it can be accomplished.

Many organizations have used log shipping very successfully by scripting all the processes such as role switching, login synchronization, and client redirects and are quickly able to fail over with minimal manual downtime. Furthermore, as log shipping involves two or more physical separate servers that do not have any shared components like a Windows failover cluster, you can achieve patch-management independence where one server is patched, the roles are switched, and then the other is patched. Data mirroring is a new high-availability technology that may eventually replace log shipping. However, log shipping is a time-tested, high-availability solution that many large, strategic customers with mission-critical applications depend on every day to provide local disaster recovery.