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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Free Buffer Waits
Obviously, you have something in your system competing for resources.
There are multiple sessions requesting the same block.
Everything seemed to run fine and now all of a sudden
things dont work , but nothing new has been introduced into the system.
How can this be ? Perhaps you have other problems that have been
created in the system in the last few days
that wont be seen until your backups are run.
It appears you are going to have to reproduce what you see and log certain events while the bottleneck is happening. I would set an event 10046 and comb through there ... I would also try to look at v$session_wait which will show the file#, clock# and id ( where id represents the status of the buffer busy wait event ).
I would also buy Gaja Krishna Vaidyanatha and Kirti Deshpande's book "Oracle Performance Tuning 101" as it has been a big help to me. Other things you might find helpful would be www.hotsos.com which goes into great detail on the 10046 event trace and they also have an excellent clinic I just went too.
Good Luck and Peace !
Mike
-----Original Message-----
Sent: Tuesday, June 18, 2002 12:43 AM
To: Multiple recipients of list ORACLE-L
Hi,
I came in early morning and saw the batch job had been taking forever. I immediately checked v$system_event (the job that took so long had just finished so session_wait was no longer option). Since we shutdown and backup our database every night the figure presented here was basically since the batch job started because that starts right after startup. So basically the system (with no other logins as per listener.ora file). had been waiting about 6-7 hours since startup on free buffer waits.
We did not introduce any other jobs to the batch and it has been running normally since that one time strange behaviour.
No logging of any hardware/software error was found on UNIX nor Symmetrix nor Oracle so we have given up for now.
Jack
"Johnson, Michael "
<Michael.Johnson_at_oln-a To: Multiple
recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
fmc.af.mil> cc: (bcc: Jack van
Zanen/nlzanen1/External/MEY/NL)
Sent by: Subject: RE: Free
Buffer Waits
root_at_fatcity.com
17-06-2002 19:28
Please respond to
ORACLE-L
Just a couple questions .....
Did you introduce any new batch jobs into the system or any other interactive jobs that may have been running at the same time ?
How do you know that the Buffer Wait event was the top wait event and how did you see this ? eg. are you taking a time slice and loggin it at certain time into a 10046 trace ,etc.
Mike
-----Original Message-----
Sent: Thursday, June 13, 2002 2:04 AM
To: Multiple recipients of list ORACLE-L
Hi All,
We have a production database that has a batch job running on it for months
now. Last night one part of the batch job that normally takes between 20-30
minutes took well over 6 hours.
The only difference I can see between today & other days is that the Free
Buffer Wait event was the top wait event, which it not normally is (not
even top 10)
This database goes down every night for backup and this is the timings I got.
Total waits:22055
Total timeouts:22052
Time waited: 2225285 (is this ms or cs?)
Avg.wait:100.8971
This whole thing puzzles me a bit since nothing changed to the database and nothing was in the Alert log. Also system was virtually idle during the 6 hours (no activity according to UNIX boys)
I was sound asleep when this happened so I don't have much more than this info.
Can anybody explain why this could have happened or point me to some documents that can. Standard answer you'll find that your DBWR can't keep up, but I have 4 of them and the sytem was idle.
THX
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Jack van Zanen INET: nlzanen1_at_EY.NL Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-LReceived on Tue Jun 18 2002 - 17:09:37 CDT
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also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Johnson, Michael INET: Michael.Johnson_at_oln-afmc.af.mil Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L
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(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Johnson, Michael INET: Michael.Johnson_at_oln-afmc.af.mil Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L
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