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

  • From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Fri, 20 Apr 2018 12:21:43 -0400

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.

Regards


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

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