Hi Andrey, yes we've checked v$session_wait and it seems kind of odd to me that wait_time is always 1 and seconds_in_wait is constantly increasing: 15:11:12 SQL> select event, p1raw, p2, state, wait_time, seconds_in_wait from v$session_wait where sid=664; EVENT P1RAW P2 STATE WTime SECONDS_IN_WAIT ------------------------------ ---------------- ----------- ------------------- ------ --------------- latch free 0700000104AA4980 98 WAITED KNOWN TIME 1 16676 15:11:43 SQL> / EVENT P1RAW P2 STATE WTime SECONDS_IN_WAIT ------------------------------ ---------------- ----------- ------------------- ------ --------------- latch free 0700000104AA4980 98 WAITED KNOWN TIME 1 16850 There haven't been any complaints from PMON in the alert log or any trace files in bdump, but it is eating up CPU like crazy, probably spinning trying to get the 'cache buffers chains' latch. There don't appear to be any other transactions rolling back: 15:27:23 SQL> select s.sid, t.addr, t.status, t.used_ublk, decode(bitand(t.flag,128),0,'NO','YES') rolling_back from v$session s, v$transaction t where s.taddr=t.addr; SID ADDR STATUS USED_UBLK ROL ----- ---------------- ---------------- ---------- --- 648 0700000105DFA1B0 ACTIVE 24 NO 1112 0700000105E57900 ACTIVE 1 NO 1055 0700000105E81250 ACTIVE 1 NO 879 0700000105E96380 ACTIVE 1 NO 737 0700000105ECABD8 ACTIVE 1 NO 1001 0700000105F52FF8 ACTIVE 1 NO 396 0700000105F90D80 ACTIVE 17 NO 664 07000001061D98D0 ACTIVE 69 YES 815 070000010620E7B0 ACTIVE 1 NO 683 0700000106267130 ACTIVE 3 NO 905 0700000106268B20 ACTIVE 1 NO 11 rows selected. We are currently looking through the hanganalyze dump. Thanks! Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it. -- //www.freelists.org/webpage/oracle-l