RE: LGWR, EMC or app cursors?

From: Herring, David <"Herring,>
Date: Mon, 7 Oct 2019 16:14:51 +0000
Message-ID: <DM6PR02MB55645B8BB805583C95A4C3B0D49B0_at_DM6PR02MB5564.namprd02.prod.outlook.com>





Chris, yeah, seems that way. I had a problem a while back where operations would timeout at seemingly random times and found out $LD_LIBRARY_PATH included a NAS that no longer existed. "strace" showed that valid paths were picked for a while, then the invalid NAS would get hit and there'd be a pause.

Anyway, the EMC config is all multipath. I'll check with storage/sysadmin teams (pretty much everything is outsourced) to review it all again.

Regards,

Dave

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From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> On Behalf Of Chris Taylor Sent: Monday, October 7, 2019 10:27 AM
To: dmarc-noreply_at_freelists.org
Cc: oracle-l_at_freelists.org
Subject: Re: LGWR, EMC or app cursors?

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Always the same database/machine?

Almost sounds like a path is down/unavailable from the machine to the storage but the OS doesn't know it isn't responding. I'm not as familiar with EMC Power and I think EMC Power uses something besides mutlipath drivers (but I might be mistaken). If you're not getting any path errors, it might be worthwhile to have someone go into the cage and replace all the Fiber cables connecting from this server to the storage (they can test the cables I believe and see if one is faulty/noisy).

Thanks,
Chris

On Mon, Oct 7, 2019 at 10:20 AM Herring, David <dmarc-noreply_at_freelists.org<mailto:dmarc-noreply_at_freelists.org>> wrote: Folks, I've got a bit of a mystery with a particular db where we're getting a periodic 25-30 pause between user sessions and LGWR processes and can't clearly identify what's the cause.

I am stuck trying to find out, really prove who is the culprit or what exactly the wait is on. Is LGWR waiting on user sessions and user sessions are waiting on LGWR and all that causes the disk to be 100%? Can I enable some sort of tracing on LGWR and would that point to exactly what he's waiting on to prove where the problem is?

Regards,

Dave











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Received on Mon Oct 07 2019 - 18:14:51 CEST

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