RE: DB TIME in AWR
From: Iggy Fernandez <iggy_fernandez_at_hotmail.com>
Date: Sun, 22 May 2016 03:36:20 -0700
Message-ID: <BLU179-W32D9A657BC6C2755778619EB4D0_at_phx.gbl>
There are many processes than there are sessions. My answer is processes * elapsed time
From the documentation: "PROCESSES specifies the maximum number of operating system user processes that can simultaneously connect to Oracle. Its value should allow for all background processes such as locks, job queue processes, and parallel execution processes." (https://docs.oracle.com/cd/B19306_01/server.102/b14237/initparams169.htm#REFRN10175) Your system will choke before it gets anywhere close to this theoretical maximum. A rule of thumb is that you should be concerned if your db time exceeds elapsed time * CPU threads; that is, if average active sessions (AAS) is greater than the number of CPU threads (threads not cores). P.S. I hope that is not an interview question. I usually fail DBA interviews because of questions like that. https://iggyfernandez.wordpress.com/2010/10/31/the-worst-interview-of-my-life/ https://iggyfernandez.wordpress.com/2012/07/16/how-not-to-interview-a-database-administrator-part-i-the-google-way/
Date: Sun, 22 May 2016 03:36:20 -0700
Message-ID: <BLU179-W32D9A657BC6C2755778619EB4D0_at_phx.gbl>
There are many processes than there are sessions. My answer is processes * elapsed time
From the documentation: "PROCESSES specifies the maximum number of operating system user processes that can simultaneously connect to Oracle. Its value should allow for all background processes such as locks, job queue processes, and parallel execution processes." (https://docs.oracle.com/cd/B19306_01/server.102/b14237/initparams169.htm#REFRN10175) Your system will choke before it gets anywhere close to this theoretical maximum. A rule of thumb is that you should be concerned if your db time exceeds elapsed time * CPU threads; that is, if average active sessions (AAS) is greater than the number of CPU threads (threads not cores). P.S. I hope that is not an interview question. I usually fail DBA interviews because of questions like that. https://iggyfernandez.wordpress.com/2010/10/31/the-worst-interview-of-my-life/ https://iggyfernandez.wordpress.com/2012/07/16/how-not-to-interview-a-database-administrator-part-i-the-google-way/
From: dba.tyagisumit_at_gmail.com
Date: Sun, 22 May 2016 15:21:58 +0530
Subject: DB TIME in AWR
To: oracle-l_at_freelists.org
On a four CPU system ( 4 CPU CORE ) , for one hour elapsed time, what
is the maximum amount of DB Time that can be accumulated?
Answer: Number of ‘sessions’ in int.ora * elapsed time = 300 * 1 hours = 300 Hours
OR
Answer : Number of ‘sessions’ in int.ora * elapsed time * CPU Cores = 300 * 1 * 4 = 1200 Hours
Which one is correct any why . Little confusion here .
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Received on Sun May 22 2016 - 12:36:20 CEST