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Question and Answer

Connor McDonald

Thanks for the question, A.

Asked: March 04, 2016 - 9:25 pm UTC

Last updated: March 06, 2016 - 12:23 pm UTC

Version: 10gR2

Viewed 1000+ times

You Asked

Hi,

We are experiencing in one of the database
log file sync average wait time close to 90 ms (consistently).
As we know it should be below 10 ms.
Your views on the poor response time which disks (NAS) is experiencing ?


Regards


and Connor said...

log file sync is not *necessarily* a disk issue.

Check the "log file parallel write" times in an AWR report. That is a better idea of the disk cost. If its large, then yes, time to look at the storage, or path to storage. If its small, then your disks are fine.

If the latter, the most common issues are:

- too frequent commits in the app
- cpu in the box is under strain

Good example of the last one here http://kevinclosson.net/2007/07/21/manly-men-only-use-solid-state-disk-for-redo-logging-lgwr-io-is-simple-but-not-lgwr-processing/

Hope this helps.


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