在alter文件中忽略该记录(二)
sage.
Increasing the value for db_writer_processes can in some situations avoid the message from being generated.
Hdr: 7005709 10.2.0.3 RDBMS 10.2.0.3 TXN MGMT LOCAL PRODID-5 PORTID-59
Abstract: LOG FILE SWITCH (PRIVATE STRAND FLUSH INCOMPLETE) WHEN _IN_MEMORY_UNDO=TRUE
PROBLEM:
--------
Oracle 10.2.0.3.0
This is a large database for Oracle Applications plus a lot of custom code.
Last night a user noticed slowness between 9 and 10 pm. When we now run AWR
and ADDM reports, we see high waits for "log file switch (private strand
flush
incomplete)".
This looks similar to Bug 6806770 except that we're HPUX 11.11, non-Itanium.
As per the bug, we currently have _in_memory_undo=TRUE.
We had this setting set to false for a while as a workaround for another bug
(5028099), but re-enabled it after applying a patch (6733906).
$ >grep memory spfilecfap.ora
*._in_memory_undo=TRUE
DIAGNOSTIC ANALYSIS:
--------------------
One night a user noticed slowness between 9 and 10 pm. When we now
run AWR and ADDM reports, we see high waits for "log file switch (private
strand flush incomplete)".
We had _in_memory_undo=FALSE from Jan 15 until March 16, when we applied
patch 6733906. Before Jan 15, we had numerous alert log messages like what's
below. Since Mar 16, we've had approx. 25 more of these messages. In
between Jan 15 and Mar 16 we had none of the messages.
Thread 1 cannot allocate new log, sequence 92288
Private strand flush not complete
WORKAROUND:
-----------
The only workaround is to set parameter _in_memory_undo = FALSE to disable
IMU
RELATED BUGS:
-------------
6806770 - still at status 11
Slow Running User Process And Top Database Wait Event Is 'log file switch (private strand flush incomplete)'
Applies to:
Oracle Server - Enterprise Edition - Version: 10.2.0.1 to 10.2.0.3 - Release: 10.2 to 10.2
Information in this document applies to any platform.
Symptoms
Checked for relevance on 31-Oct-2011
A user process is running very slow and the top database wait event is always 'log file switch (private strand flush incomplete)'.
AWR Report shows the following Top 5 Timed Events.
log file switch (private strand flush incomplete)
buffer busy waits
log file sync
db file sequential read
log file switch (checkpoint incomplete)
Cause
Unpublished Bug 5605290 which causes deadlocks between the CKPT and LGWR or DBWR processes, and can manifest itself in many ways.
Solution
Unpublished Bug 5605290 is fixed in the 10.2.0.4 patchset, so applying it will resolve this issue. In addition there is a workaround available to prevent the problem until able to get the database patched up.
sqlplus / as sysdba
alter system set "_in_memory_undo" = FALSE scope=both;