ORA-00494: enqueue [CF…

tarting background process CJQ0

Sat Oct 13 06:57:49 2012

CJQ0 started with pid=96, OS id=8195

Sat Oct 13 07:18:04 2012

Suspending MMON slave action kewrmafsa_ for 82800 seconds

Sat Oct 13 07:53:05 2012

Process 0x51000b020 appears to be hung while dumping

Sat Oct 13 07:58:28 2012

Current time = 315551548, process death time = 315488216 interval =
60000

Sat Oct 13 08:09:19 2012

Errors in file
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/trace/TEST2_arc1_26225.trc 
(incident=30460):

ORA-00494: enqueue [CF] held for too long (more than 900 seconds)
by 'inst 1, osid 26205'

Sat Oct 13 08:11:19 2012

WARNING: aiowait timed out 1 times

Incident details in:
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/incident/incdir_30460/TEST2_arc1_26225_i30460.trc

Sat Oct 13 08:16:53 2012

Attempting to kill process 0x51000b020 with OS pid = 5332

OSD kill succeeded for process 51000b020

Sat Oct 13 08:16:53 2012

Errors in file
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/trace/TEST2_arc2_20128.trc 
(incident=30660):

ORA-00494: enqueue [CF] held for too long (more than 900 seconds)
by 'inst 1, osid 26205'

Incident details in:
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/incident/incdir_30660/TEST2_arc2_20128_i30660.trc

Sat Oct 13 08:16:53 2012

Errors in file
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/trace/TEST2_arc0_26223.trc 
(incident=30644):

ORA-00494: enqueue [CF] held for too long (more than 900 seconds)
by 'inst 1, osid 26205'

Incident details in:
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/incident/incdir_30644/TEST2_arc0_26223_i30644.trc

Sat Oct 13 08:16:53 2012

Errors in file
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/trace/TEST2_arc3_26229.trc 
(incident=30476):

ORA-00494: enqueue [CF] held for too long (more than 900 seconds)
by 'inst 1, osid 26205'

Incident details in:
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/incident/incdir_30476/TEST2_arc3_26229_i30476.trc

Sat Oct 13 08:16:56 2012

Process W000 died, see its trace file

Sat Oct 13 08:17:16 2012

Sat Oct 13 08:17:16 2012

Killing enqueue blocker (pid=26205) on resource
CF-00000000-00000000

Killing enqueue blocker (pid=26205) on resource
CF-00000000-00000000

 by killing session 191.1

 by killing session 191.1

Killing enqueue blocker (pid=26205) on resource
CF-00000000-00000000

 by terminating the process

Killing enqueue blocker (pid=26205) on resource
CF-00000000-00000000

ARC1 (ospid: 26225): terminating the instance due to error
2103

 by terminating the process

Sat Oct 13 08:17:16 2012

Killing enqueue blocker (pid=26205) on resource
CF-00000000-00000000

 by killing session 191.1

Killing enqueue blocker (pid=26205) on resource
CF-00000000-00000000

 by terminating the process

Sat Oct 13 08:17:16 2012

Errors in file
/pool02/test2/db/tech_st/11.1.0/log/diag/rdbms/test2/TEST2/trace/TEST2_smon_26207.trc:

ORA-02103: PCC: inconsistent cursor cache (out-of-range cuc
ref)

Termination issued to instance processes. Waiting for the processes
to exit

Sat Oct 13 08:17:26 2012

Instance termination failed to kill one or more processes

Instance terminated by ARC1, pid = 26225

 

Cause:

进程LGWR杀死了ckpt进程，进而引起数据库宕机。

l  数据库长时间等待CF enqueue，以致报：ORA-00494: enqueue
[CF] held for too long (more than 900 seconds) by 'inst 1, osid
38356'

l 
然后LGWR进程杀死了其阻塞进程，本例中LGWR进程kill了ckpt进程，所以导致数据库实例CRASH。

在这种情况下，我们也通常会发现联机日志文件切换相当频繁。

 

Solution:

Oracle通常建议联机日志切换时间间隔为20-30分钟，以降低控制文件的contention。

可以通过查询视图V$INSTANCE_RECOVERY.OPTIMAL_LOGFILE_SIZE，该列是以兆为单位，如果联机日志文件的实际大小小于该建议值的话，那么Oracle建议将文件大小调整为建议值。