Olha a que usamos no meu trabalho: jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=oracore01-vip.i.tj.pa.gov.br)(PORT=1521))(ADDRESS=(PROTOCOL=TCP)(HOST=oracore02-vip.i.tj.pa.gov.br)(PORT=1521))(LOAD_BALANCE=yes)(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=libra)(FAILOVER_MODE=(TYPE=SELECT)(METHOD=BASIC)(RETRIES=180)(DELAY=5))))