its just a session id, they are not unique across instances, a session id is not a database connection, its an instance connection and a session will only exist on one instance And that is not how load balancing works On 27/09/2007, qihua wu <staywithpin@xxxxxxxxx> wrote: > > We have a two nodes RAC, the strange thing is that many sessions run on > both nodes. > select sid from gv$session group by sid having count(*)>1 > they are lots of rows return. > > My understanding for load balance is: if sessions on instance 1 are too > many, then new session will be connected to instance 2. > But if at the beginning there were100 sessions on both inst1 and inst2, > after all the sessions on inst2 are completed, no existing session on > instance1 will go to instance2. > > But the fact of the above query told me some sessions run on both > instance. How can this be true? > >