Re: what is "kfk: async disk IO"?
- From: Martin Berger <martin.a.berger@xxxxxxxxx>
- To: D'Hooge Freek <Freek.DHooge@xxxxxxxxx>
- Date: Tue, 7 Dec 2010 11:50:18 +0100
Freek,
thank you for your clarification.
Currently I'm not so much on the performance tuning side. It's more a kind of
troubleshooting, where I still does not know how to catch the situation.
Some minutes after my observation the instance hang as all sessions where used
- not even sys could logon. (yes, prelim worked, but that's not the issue here).
No, my colleague did not create a systemdump or hanganalyze or similar....
Even it's only a 'test' system we had to restart the instance. Without any big
investigation.
Now I'm searching what this "kfk: async disk IO" is. Maybe someone has some
infos about P1, P2, P3. I will try to grab some informations out of ASH or
other resources, based on this.
Martin
Am 07.12.2010 um 10:42 schrieb D'Hooge Freek:
> Martin,
>
> The "kfk: async disk IO" seems to be linked to the io_submit system call.
> You could check your number of async io processes.
>
> But don't look at the number of occurrences to determine how "heavy" an event
> is, look at the time spend. There is no relation between number of
> occurrences and time spend.
>
>
> Regards,
>
>
> Freek D'Hooge
> Uptime
> Oracle Database Administrator
> email: freek.dhooge@xxxxxxxxx
> tel +32(0)3 451 23 82
> http://www.uptime.be
> disclaimer: www.uptime.be/disclaimer
> --
> From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
> Behalf Of Martin Berger
> Sent: dinsdag 7 december 2010 9:50
> To: Oracle-L Freelists
> Subject: what is "kfk: async disk IO"?
>
> Hi,
>
> can anyone please hint me to some information about
> kfk: async disk IO ?
>
> A little query on v$sessions gave me
> USERNAME EVENT
> COUNT(*)
> ------------------------------
> -------------------------------------------------- ----------
> APPS ges message buffer allocation
> 98
> APPS CSS operation: action
> 2
> APPS Streams AQ: waiting for messages in the queue
> 9
> SYS SQL*Net message to client
> 1
> APPS SQL*Net message from client
> 147
> APPS kfk: async disk IO
> 1646
>
> as kfk: async disk IO is the bigest contributor, I'd like to investigate a
> little bit.
>
> for the records: 11.2.0.1 - 2 node RAC - RedHat 5.4 Linux 64-bit. (yes, it's
> EBS - but don't ask me the exact pach level, please - I assume 11.5.10???)
>
> thnx
> Martin
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