Use SQL Server clustering when you want a hot, standby, failover support. Clustering offers automatic detection of server failure and automatic failover between nodes participating in the cluster. Client application connections can automatically be redirected to the current active server instance and application data requests will be serviced with little or no interruption.

Use log shipping when you want a warm standby solution. Log shipping transfers database dumps and logs from the primary server to the secondary server. As with any warm standby solution, failure detection and failover processing is not automated. When log shipping is employed, the standby database cannot be used for data access. The standby database is unavailable throughout the continual process of loading database and transaction log dumps from the primary server. Because log shipping transfers complete database logs, all logged schema and data changes are transferred from the primary to secondary node. When log shipping is employed, it is not possible to partition the data or transfer only a subset of the objects from the database.

Use replication when you want a warm standby solution, and when simultaneous data access on the secondary node (scale out for read) or object or data partitioning is a requirement.