Metrics "Database Time Spent Waiting (%)" is at 83.25965 for event class

Question

Hello,
when i log into em console, i have alert below,
"Metrics "Database Time Spent Waiting (%)" is at 83.25965 for event class "Commit"
so, what do i need to do? i have no idea about this,
is it a critical error? is there any solution?
thank you
Ugur

Answer 1

Ugur MIHCI wrote:
Hello,
when i log into em console, i have alert below,
"Metrics "Database Time Spent Waiting (%)" is at 83.25965 for event class "Commit"
so, what do i need to do? i have no idea about this,
is it a critical error? is there any solution?
thank you
UgurProbably what you would want to do in this case is to first determine which wait events are in that event class:
{code}
SELECT
NAME
FROM
V$EVENT_NAME
WHERE
WAIT_CLASS='Commit';
NAME
log file sync
enq: BB - 2PC across RAC instances
{code}
If you are not using RAC, the second of the above wait events probably does not apply. Next, you need to determine what the "log file sync" wait means, so you might do a Google search of the Oracle documentation. Assume that you are using Oracle Database 10.2.0.x - you would then search for:
{code}
site:download.oracle.com "log file sync" 102
{code}
In my search, the first link was a page from the Oracle Database Performance Tuning Guide:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/instance_tune.htm
That page contained the following quote:
"log file sync
General area: I/O, over- committing
Possible cause: Slow disks that store the online logs, Un-batched commits
Look for: Check the disks that house the online redo logs for resource contention. Check the number of transactions (commits + rollbacks) each second, from V$SYSSTAT."
Excessive waits for log file sync may also be caused by lack of available CPU time - an overloaded CPU.
Charles Hooper
Co-author of "Expert Oracle Practices: Oracle Database Administration from the Oak Table"
http://hoopercharles.wordpress.com/
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.