A warm standby application is a pair of databases, one of which is a backup copy of the other. Client applications update the active database; SAP Replication Server maintains the standby database as a copy of the active database.
The SAP Replication Server warm standby application for SAP ASE databases is described in Managing Warm Standby Applications in the Administration Guide Volume 2.
For detailed information about how Failover support works in SAP Replication Server, see Configure the Replication System to Support SAP Failover and High Availability on Sun Cluster 2.2 in the Administration Guide Volume 2.