Re: troubleshooting slow I/O performance.

Hello Chris,
at first you need to identify where the time is spent in the whole I/O stack (e.g. I/O scheduler, SCSI, etc.).

For example you can do that with blktrace on Linux: http://www.fis.unipr.it/doc/blktrace-1.0.1/blktrace.pdf

Anything further is related to this drill-down outcome :-)

Best Regards
Stefan Koehler

Independent Oracle performance consultant and researcher Website: http://www.soocs.de
Twitter: _at_OracleSK

> Chris Stephens <cstephens16_at_gmail.com> hat am 7. Mai 2018 um 15:59 geschrieben:
>
> We have a new 5 node 12.2 RAC system that is not performing the way we want. 
>  
> The glaring issue is that "db file sequential read"'s are taking ~10ms. before i lob this over to the storage administrators, are there any possible areas in the clusterware/database configuration that I should investigate first? i have root access to all of the nodes. is there any information i can collect that would expedite the process of figuring out why we have such slow I/O times?
>  
> slow i/o was discovered by running slob. if you don't know about that tool, you should. we all owe kevin a debt of gratitude. ;)
>
>  
> if nothing else, i hope to learn a little more about storage than i currently know (which isn't much).
>  
> thanks for any help.  
>  
> chris

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