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Interpretation of Oracle Metrics [message #520658]

Tue, 23 August 2011 17:21

taylorf20850
Messages: 5
Registered: August 2011
Location: Rockville, Md

Junior Member

When looking at some of the metrics available in OEM, I am puzzled by the interpretation:

1) Using the Host tab, and load metrics, I can get a metric for the Total I/O for the host .. I assume this is IOPS.

2) Using the Database tab, and the instance_throughput physreads_pc metric I can get a metric for the Physical Reads from the database instance per second.

3) We generally have several Oracle instances on the same server, and in all cases, the sum of the physical reads for each database is SIGNIFICANTLY higher that the total i/o for the host.

Am I interpreting the information incorrectly ?
Does one of the metrics consider db_block_size ?
Has anyone seen this ?

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Re: Interpretation of Oracle Metrics [message #520660 is a reply to message #520658]

Tue, 23 August 2011 17:27

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

I suggest you use OS utilities to measure System level metrics & ignore of those reported by any RDBMS.

It would be helpful if you followed Posting Guidelines - http://www.orafaq.com/forum/t/88153/0/

answer may also be OS dependent, but you decided we did not need to know yours.

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Re: Interpretation of Oracle Metrics [message #520673 is a reply to message #520658]

Tue, 23 August 2011 21:45

taylorf20850
Messages: 5
Registered: August 2011
Location: Rockville, Md

Junior Member

You are right, I forgot to mention the OS/DB version.

I'm using OEM 1.2.0.5

Oracle 10.2.0.4 and 11.2

All on Solaris 10, but we are now adding Linux hosts.

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Re: Interpretation of Oracle Metrics [message #520677 is a reply to message #520673]

Tue, 23 August 2011 23:11

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

>All on Solaris 10, but we are now adding Linux hosts.

sar provides all necessary OS statistics

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Re: Interpretation of Oracle Metrics [message #520814 is a reply to message #520677]

Wed, 24 August 2011 17:47

taylorf20850
Messages: 5
Registered: August 2011
Location: Rockville, Md

Junior Member

I'm interested in OEM data, since sar can only give me server statistics, not database statistics. OEM gathers the sar information and loads the metrics into the repository. I can see the total I/O from the server side, but the database numbers are puzzling... For example:

Solaris 10 Server, SUN V490, 32GB mem, has 12 databases.

From the server stats I see average of the last month without weekends, of 232 i/o per second.

When I sum the average reads(2,448) and writes(82) for 2,530 I/O per second..

There is about 10x difference.

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Re: Interpretation of Oracle Metrics [message #520817 is a reply to message #520814]

Wed, 24 August 2011 19:40

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

>OEM gathers the sar information and loads the metrics into the repository.

I suggest you submit a Service Request to obtain official response to this purported discrepancy.

If sar is not enabled (no cron job to periodically collect sar statistics; since it optional), does OEM cease to report OS statistics?

How does OEM collect & report OS statistics on Windows systems?

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