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

From: Mladen Gogala <>
Date: Fri, 20 Apr 2018 12:21:43 -0400
Message-ID: <>

Hi Purav,

Please install iotop or atop on the machines, so that you are able to tell which process is responsible for the 100% utilization.


On 04/18/2018 01:25 PM, Purav Chovatia wrote:
> 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

Mladen Gogala
Database Consultant
Tel: (347) 321-1217

Received on Fri Apr 20 2018 - 18:21:43 CEST

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