postgresql 8.1.11 we found the database can't be connected at 2014/5/9 23:00 and 2014/5/10 17:03 which you can see from below log. We checked the CUP and memory also, it is normal. And the server generated many postmaster process at the interrupted time. Untill we restart the database, it becomes normal. So why this could happens? DB log : 5/9 23:00 ~ 00:00 tail postgresql-Fri.log [PID=16483]: [user=ec_operator,db=eservice,ip=10.100.66.37][time=2014-05-09 23:00:03 CST]LOG: duration: 0.024 ms [PID=16485]: [user=ec_operator,db=eservice,ip=10.100.66.37][time=2014-05-09 23:00:03 CST]LOG: statement: <BIND> head postgresql-Sat.log [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: database system was interrupted at 2014-05-09 23:01:04 CST [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: checkpoint record is at CCF/66A731F8 [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: redo record is at CCF/66A731F8; undo record is at 0/0; shutdown FALSE [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: next transaction ID: 1752693096; next OID: 1143806 [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: next MultiXactId: 1; next MultiXactOffset: 0 [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: database system was not properly shut down; automatic recovery in progress [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: record with zero length at CCF/66A73248 [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: redo is not required [PID=5263]: [user=,db=,ip=][time=2014-05-10 00:15:58 CST]LOG: database system is ready 5/10 19:00~20:00 [PID=13060]: [user=ec_operator,db=eservice,ip=10.100.66.37][time=2014-05-10 19:03:21 CST]LOG: statement: EXECUTE <unnamed> [PREPARE: select currval('public.ec_messagebackup_id_seq')] [PID=13060]: [user=ec_operator,db=eservice,ip=10.100.66.37][time=2014-05-10 19:03:21 CST]LOG: duration: 0.032 ms [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: database system was interrupted at 2014-05-10 19:05:21 CST head 2014051020_21 [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: database system was interrupted at 2014-05-10 19:05:21 CST [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: checkpoint record is at CD2/41498F80 [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: redo record is at CD2/41498F80; undo record is at 0/0; shutdown FALSE [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: next transaction ID: 1754216008; next OID: 1151998 [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: next MultiXactId: 1; next MultiXactOffset: 0 [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: database system was not properly shut down; automatic recovery in progress [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: record with zero length at CD2/41498FD0 [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: redo is not required [PID=19628]: [user=,db=,ip=][time=2014-05-10 20:52:24 CST]LOG: database system is ready -- View this message in context: http://postgresql.1045698.n5.nabble.com/database-system-was-interrupted-sometimes-untill-we-restart-it-can-be-used-tp5805533.html Sent from the PostgreSQL - general mailing list archive at Nabble.com.