Dear Oracle Gurus This is my environment-Oracle11g 11.2.0.3.0- 2 Node RAC with Oracle ASM in RHEL 6.4 64bit platform Last night our node-2 was restarted and we checked below error After reboot one of the app query taking more time as shown in alert logs Tue Apr 08 05:19:52 2014 Active Session History (ASH) performed an emergency flush. This may mean that ASH is undersized. If emergency flushes are a recurring issue, you may consider increasing ASH size by setting the value of _ASH_SIZE to a sufficiently large value. Currently, ASH size is 33554432 bytes. Both ASH size and the total number of emergency flushes since instance startup can be monitored by running the following query: select total_size,awr_flush_emergency_count from v$ash_info; Tue Apr 08 05:54:06 2014 ORA-01555 caused by SQL statement below (SQL ID: gn175954b63p2, Query Duration=7609 sec, SCN: 0x0072.e21901ea): UPDATE MYTABLE SET EMAILSTATUS = :1 , SMSSTATUS = :2 , SERVERINSTANCEID = :3 WHERE EMAILSTATUS = :4 AND SMSSTATUS = :5 Tue Apr 08 06:07:54 2014 ORA-01555 caused by SQL statement below (SQL ID: gn175954b63p2, Query Duration=8347 sec, SCN: 0x0072.e21a485d): UPDATE MYTABLE SET EMAILSTATUS = :1 , SMSSTATUS = :2 , SERVERINSTANCEID = :3 WHERE EMAILSTATUS = :4 AND SMSSTATUS = :5 any faced the same issue, please suggest us the valuable input Thanks Hitgon