RE: wait events and v$session

From: Cary Millsap <cary.millsap_at_hotsos.com>
Date: Tue, 11 May 2004 10:33:20 -0500
Message-ID: <004601c4376d$4d6a1fa0$6601a8c0@CVMLAP02>

Right. The "global cache *" timed events indicate time spent maintaining the coherency of the 2+ participating database buffer caches. One note worth mentioning here is that even the famous "I'll do TP on one RAC node and query-only on the other" strategy is prone to lots of "global cache *" activity.

Why? Because of the undo blocks that are used by both nodes.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *

Upcoming events:
- Performance Diagnosis 101: 5/18 Edison NJ, 6/22 Pittsburgh, 7/20 Boston

SQL Optimization 101: 5/24 San Diego, 6/14 Chicago, 6/28 Denver
Hotsos Symposium 2005: March 6-10 Dallas
Visit www.hotsos.com for schedule details...

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Jamadagni, Rajendra
Sent: Tuesday, May 11, 2004 10:08 AM
To: oracle-l_at_freelists.org
Subject: RE: wait events and v$session_event

RAC Cache fusion waits are not sue to load balancing ... They are due to the fact that you are running RAC, you will see these waits even if you are running single node in the RAC.=20

Raj

--------=20
Rajendra dot Jamadagni at nospamespn dot com=20 All Views expressed in this email are strictly personal.=20 select standard_disclaimer from company_requirements;=20 QOTD: Any clod can have facts, having an opinion is an art !

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of ryan.gaffuri_at_cox.net Sent: Tuesday, May 11, 2004 10:33 AM
To: oracle-l_at_freelists.org
Subject: wait events and v$session_event

I have one batch process running and there are alot of waits. I thought waits were caused by concurrency?=20

If this is unreadable, please ignore. Hard to format with web email. Basically, I have large waits for DB_FILE_SCATTERED_READ, DB_FILE_SEQUENTIAL_READ, and for RAC Cache Fusion due to the load balancing.=20

     SID EVENT                          TOTAL_WAITS TOTAL_TIMEOUTS

TIME_WAITED AVERAGE_WAIT MAX_WAIT TIME_WAITED_MICRO

---------- ------------------------------ ----------- --------------
----------- ------------ ---------- -----------------
        22 rdbms ipc reply                          1              0
0            0          0               165
        22 log file sync                            1              0
0            0          0               996
        22 db file sequential read             491250              0
23237            0        172         232371459
        22 db file scattered read              159243              0
29892            0         37         298924960
        22 global cache open x                     10              0
0            0          0              3380
        22 global cache s to x                  11273              0
648            0         42           6477337
        22 global cache cr request            1453244             16
233740            0         98        2337401155
        22 row cache lock                         210              0
14            0          0            135414
        22 library cache lock                      15              0
1            0          0              5311
        22 SQL*Net message to client               21              0
0            0          0                27
        22 SQL*Net message from client             21              0
1            0          0              9023


----------------------------------------------------------------

Please see the official ORACLE-L FAQ: http://www.orafaq.com

To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line.

--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------

----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request_at_freelists.org
put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------

Received on Tue May 11 2004 - 10:35:02 CDT