Use the unixODBC Driver Manager or the Sybase iAnywhere ODBC Driver Manager to failover on UNIX platform.
# odbcinst -i -s -f dsn template file
where dsn template file is the complete path to the Adaptive Server ODBC datasource template file.
[sampledsn] Driver=Adaptive Server Enterprise Server=sampleserver Port=4100 UserID=sa Password= Database=pubs2 HASession=1 SecondaryHost=failoverserver SecondaryPort=5000