Ora-00494: Enqueue [Cf] Held For Too Long

Applies to Oracle 11.1.0.9 Single Instance running on OEL 5 X86_64

Problem: One of our QA Databases crashed due to the following error:

Tue Jan 17 12:53:12 2012
Errors in file /u01/app/oracle/diag/rdbms/myQAdb/MYQADB/trace/MYQADB_lgwr_616.trc  (incident=203762):
ORA-00494: enqueue [CF] held for too long (more than 900 seconds) by 'inst 1, osid 796'
Incident details in: /u01/app/oracle/diag/rdbms/myQAdb/MYQADB/incident/incdir_203762/MYQADB_lgwr_616_i203762.trc
Killing enqueue blocker (pid=796) on resource CF-00000000-00000000
by killing session 1086.1
Tue Jan 17 12:53:16 2012
Sweep Incident[203762]: completed

Prior to the database crash we were seeing errors from OEM

Message=1 distinct types of incidents have been found in the alert log.

Metric=Generic Incident Status

Having looked into the errors in the alert log and the subsequent database crash at 12:53, it seems the issue was caused by the database running out of memory

Full details are given here: Ora-00494: Enqueue [Cf] Held For Too Long Causing Database To Crash [ID 1101862.1]

within MYQADB_lgwr_616_i203762.trc trace file

loadavg : 0.12 0.11 0.09

memory info: free memory = 0.00M

swap info:   free = 0.00M alloc = 0.00M total = 0.00M

F S UID        PID  PPID  C PRI  NI ADDR SZ WCHAN  STIME TTY          TIME CMD

0 S oracle     796     1  0  75   0 – 1696141 -    Jan10 ?        00:00:28 ora_arc2_MYQADB

We bounced both the database and the server to clear memory which seemed to resolve the issue. We have not had the Enqueue error since then.

The solution being offered on the metalink note is If RAM > 8192MB then swap should be .75 times RAM, however the memory on the server is already correctly set.

This is one we will just be keeping an eye on…

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