Re: IO Freeze ON RHEL 6.6 and hence high log file sync

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Wed, 18 Apr 2018 19:51:02 +0000
Message-ID: <LO1P123MB097746CF7927D1C12BA8571AA5B60_at_LO1P123MB0977.GBRP123.PROD.OUTLOOK.COM>

The last time this happened to me it was because the disk system had decided to do a diagnostic self-check every 15 minutes - I can't remember why, though.

Regards
Jonathan Lewis

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From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> on behalf of Purav Chovatia <puravc_at_gmail.com> Sent: 18 April 2018 18:25
To: oracle-l_at_freelists.org
Subject: IO Freeze ON RHEL 6.6 and hence high log file sync

We are on RHEL 6.6 running a 2-node Oracle 12c RAC.

All of a sudden, for 2-3 minutes, DATADG (asm diskgroup containing all data files) freezes for 2-3minutes with iostat showing 100% utilisation, very high svctm and very high write_await. But the r/s, w/s rsec/s and wsec/s is 0. Meaning no IO but still disk fully busy. So it’s like a freeze.

Has anybody experienced this and can somebody help as to what could be the reason?

Transparent huge pages were not disabled and general huge pages were not configured. Now both done.

Many thanks

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Received on Wed Apr 18 2018 - 21:51:02 CEST