Re: Swapping Issues and ora_dbw
- From: Niall Litchfield <niall.litchfield@xxxxxxxxx>
- To: Iggy Fernandez <iggy_fernandez@xxxxxxxxxxx>
- Date: Tue, 7 Oct 2014 16:49:16 +0100
In addition to all the good feedback above (the pythian doc is excellent) ,
what value do you have set for vm.swappiness? The default is 60, but for an
Oracle database server that doesn't really make much sense.
http://www.redhat.com/rhecm/rest-rhecm/jcr/repository/collaboration/jcr:system/jcr:versionStorage/ee6fe0000a0526020f35498ae39e9939/14/jcr:frozenNode/rh:resourceFile
suggests setting this to zero (as do I) however I don't find any official
Oracle recommendations on this other than for old kernel versions and RAC
databases.
On Tue, Oct 7, 2014 at 4:20 PM, Iggy Fernandez <iggy_fernandez@xxxxxxxxxxx>
wrote:
> Hi, Hilton,
>
> You did not include the column headings but the reported memory
> consumption probably includes the SGA size and shared binary code (the
> Oracle executable itself and the shared libraries) in addition to private
> memory. For example, read
> http://www.pythian.com/blog/oracle-instance-memory-usage/.
>
> Also, would you explain "running out of swap space" with numbers. See for
> example,
> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/5/html/Tuning_and_Optimizing_Red_Hat_Enterprise_Linux_for_Oracle_9i_and_10g_Databases/sect-Oracle_9i_and_10g_Tuning_Guide-Swap_Space-Checking_Swap_Space_Size_and_Usage.html
> .
>
> If I were to guess, you have large SGAs and/or lots of connections some of
> which may have large PGAs.
>
> Iggy.
>
> ------------------------------
> From: hilton@xxxxxxxx
> To: oracle-l@xxxxxxxxxxxxx
> Subject: Swapping Issues and ora_dbw
> Date: Tue, 7 Oct 2014 09:25:18 +0000
>
>
> Hi there,
>
>
>
> I have a test server with three instances running and I have been seeing
> that swapping issues.
>
> The server is running out of swap space, been flirting on the edge of 0.
>
> I dug a little deeper an found that the main culprits are two of the
> instances:
>
>
>
> 49069 oradev 20 0 12.2g 10g 10g S 0.0 21.5 40:44.19
> ora_dbw0_DEV
>
> 49073 oradev 20 0 12.2g 10g 10g S 0.0 21.5 40:43.90
> ora_dbw1_DEV
>
> 4716 orapatch 20 0 12.2g 8.5g 8.5g S 0.0 17.9 33:20.19
> ora_dbw1_PATCH
>
> 4712 orapatch 20 0 12.2g 8.4g 8.4g S 0.0 17.9 31:45.49
> ora_dbw0_PATCH
>
>
>
> The weird thing is the third instance does not register although they are
> the same clone from the Production instance.
>
> Few questions:
>
> · Is this not an unusually high percentage of memory for the
> process to hold?
>
> · Is there a way to release the memory back to the server?
>
> · Is there a way for me to dig deeper to find out why these two
> instances are holding so much memory?
>
>
>
>
>
> Sys Info:
>
> EBS R12.1.3
>
> Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit
> Production
>
> Linux 2.6.39-400.210.2.el5uek
>
>
>
> Thanks,
>
>
>
> *Hilton Meyer*
>
> Database Administrator
>
>
>
> *Phone: *+972-52-7908599
>
> *Office: *+972-52-7908600* Fax: *1535-27908600
>
> hilton@xxxxxxxx | www.komit.co
>
>
>
> [image: Description: Description: Description: komitlogoDsigniture]
>
>
>
--
Niall Litchfield
Oracle DBA
http://www.orawin.info
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