Note about Services and Load Balancing Advisory

There are two types of load balancing that you can implement:

1.  Client-side:  Balance the connections across the listeners
2.  Server-side:  The listener directs the connection requests to the best instance based on the load balance advisory (LBA).

You can use LONG or SHORT load balancing methods.  Just like its name, LONG is suitable for long-lived connections like connection pools and SQL*Forms.  SHORT is suitable for short-lived connections like ORDER service type..

ex:  srvctl modify service -d labbdr -s labbpoc -q TRUE -P BASIC -e SELECT -z 180 -w 5 -j LONG
(e:  failover method, z:  number of retries, w:  delay between, j:  load balancing goal

Load Balancing Advisory (LBA):  Advisory to send works across instance and is available for applications JDBC, ODP.  There are two types of service level goals:

1.  SERVICE_TIME:  based on the elapse time for work to be done where the rate of demands change.  Open orders, internet shopping type of workloads

ex:    srvctl modify service -d DBAPOC -s DBA_RAC -B SERVICE_TIME -j SHORT

2.  THROUGHPUT:  direct works according to throughput and suitable for workload like batch processing..
ex:    srvctl modify service -d DBAPOC -s dbatplt_rac -B THROUGHPUT -j LONG

Monitor service
select machine, failover_method, failover_type, failed_over, service_name, count(*) from v$session
group by machine, failover_method, failover_type, failed_over, service_name