I make a pardon, didnt look properly your query. So your situation is node 1 -> 100 sessions node 2 -> 100 sessions After a while node 2's sessions are closed and should be gone but you still see them, have you checked logon_time and see if the sessions in node 2 are actually the old sessions which are supposedly closed? Are you using Client-Server or Three Tier? Thanks -- LSC On 9/27/07, 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? > > > > >